The highest likelihood of Spurs getting a penny from the deal is that Dele has a good pre-season, a good August, and that Everton decide to pay the £10m.
Renogotiating the deal makes it less likely Everton will pay anything for him on account that he's closer to the end of his contract with us.
The first part of that isn't going to happen (we can't pay 10m to play him for less than one full seasons worth of games) so it's the exact opposite really: renegotiating the deal is the only way Everton will pay anything for him.
The fact that he's in the final year of his deal emphasises that, because even if we did pay the money and put the work into helping him get his game back, then if he did go on to have a really good season he could still leave and we get nothing for the expense and hard work.
In fact, if we do negotiate a flat fee that lets us play him an unlimited number of games, we probably still need to renegotiate his contract on top of that too, to give us the option to extend by at least a year to avoid that sort of scenario.