The Daily Mail reported on Friday that the two clubs have held talks on what would be a permanent deal.
So what’s the state of play and what might happen next?
We take a look at some of the key questions and what will be the key to an ambitious move...
Sunderland's Championship rivals Wigan beat Rotherham to ex-SAFC striker signing
Five strikers Sunderland could sign - including Leeds United, Southampton and Peterborough United stars
These are the Stadium of Light changes Sunderland and QPR fans need to be aware of
Sunderland transfer news: New signings ex-Cardiff City and Morecambe duo outline what they'll bring to U21 group
How QPR are expected to start against Sunderland - with several injury concerns for Michael Beale's side
How keen are Sunderland on a deal?
Sunderland want to keep the core of last season's squad together and build on it.
Clearly, Clarke is a part of that and Sporting Director Kristjaan Speakman hinted strongly that the club would explore the possibility after the win at Wembley.
“We’re really pleased with all our loans, they’ve made an impact at times along the way,” he said.
“We’ll definitely be investigating whether some of those players could come back to us but we have to be respectful of the fact that they are not our players.
“It’s not always easy to turn a loan into a permanent one but if it’s right for everyone, there’s a deal to be done."
Does Clarke have a future at Spurs?
Clarke's future has not been publicly discussed by Spurs but an aggressive recruitment drive by the club this summer means competition for places is ferocious.
Realistically, Clarke's two potential avenues into the Spurs squad would be either as wing back or in one of the three central attacking roles in Antonio Conte's 3-4-3. At wing back, Ivan Perisic has already been recruited and it is expected that Djed Spence will follow.
In the forward areas, Dejan Kulusevski made a major impact in the second half of last season and Richarlison has now arrived to add even more depth.
In theory Clarke could play his way into the club's plans through pre-season but at this moment it appears unlikely. You can certainly see why all parties would be open to exploring a potential move.
Sunderland want a permanent deal - is it feasible?
It would be a complex deal but one that is definitely feasible.
Spurs are believed to have paid in the region of £10 million to sign Clarke from Leeds United in 2019, and clearly they will be reluctant to make a significant loss on that deal. At that kind of price, it is immensely unlikely that Sunderland would be in equation.
What changes the picture is that Clarke has just moved into the last year of his current contract.
At this stage, it takes a loan move out of the equation. That doesn't work for Spurs, raising the prospect of Clarke building interest but then being available on a free.
It also means that Spurs have to consider a sale if they don't feel there is a realistic chance of agreeing a new deal, as it will be their last chance to recoup some of that initial investment.
They can also protect against Clarke taking his career to the next level at Sunderland by including a sell-on clause and some performance related add-ons.
Those clauses could potentially help bridge the gap between the two clubs financially.
Sunderland are determined not to spend beyond their means in their first season back but their move for Dan Ballard showed that they are prepared to pay significant fees where they believe there could be significant resale value. One of the largely unknown factors at this point is to what extent clubs who may have bigger budgets than Sunderland this summer are also interested in the 21-year-old.
They also still have five loans slots which are currently unused, which can help balance their investment over the course of the summer.
How does the deal fit into Sunderland's transfer puzzle?
Though Alex Neil played primarily with a back three after arriving at Sunderland, that was primarily because he felt it was necessary to deal with an initial shortage of defensive options and an unusual vulnerability to the counter attack. This was something that waned as Corry Evans found form and Danny Batth returned to fitness.
The three play-off games saw Neil stick with a 4-2-3-1 system, one that he has deployed for the vast majority of his managerial career.
It's likely that Sunderland will operate with this system a lot this season, which means four wingers are a must (though of course Elliot Embleton also operates out wide to great effect).
With Clarke, Patrick Roberts and Leon Dajaku, Neil would have a strong base.
That would of course also leave the club with a decision to make over Jack Diamond, who has a big chance to make an impression in pre-season while talks over numerous transfer targets continue. A loan to League One could be a possibility.
Sunderland have also made significant bids for Jack Rudoni, the AFC Wimbledon playmaker who can also operate in the wide positions.
So far they have yet to meet the Dons' valuation but creatively it would leave Sunderland very well stocked.
On both fronts, there is clearly still a lot of work to do.
Phil’s verdict - a deal worth doing?
This would be a massive boost for Sunderland were they able to pull it off.
Clarke initially struggled for consistency after joining in January but remember that he was often playing in a relatively unfamiliar wing back role.
As the season progressed he got better and better and his performances alongside Roberts were a glimpse of an exciting future.
Add to the mix that he now also significant Championship experience, and by coming through at Leeds United in the pressure of a promotion push has proved he can handle the pressure of a big club.
Providing the fee is sensible, and the Black Cats won't do it if it isn't, it's a move that perfectly reflects the new Sunderland model.
He is ready to make a mark, but also still has significant room to grow.