The England international has agreed a move to MLS side Toronto at the end of February but will sit out the second leg of Spurs' Europa League last-32 tie with Dnipro on Thursday due to a hamstring injury.
The 31-year-old, who broke Martin Chivers's club record of 22 European goals with a penalty in the 2-1 win over Sheriff in November, has been a huge hit over two spells in north London and his boss believes that he is among the club's all-time greats.
"Let's hope we can find another like Jermain Defoe because he's all about goals. Whenever he pulled on the Tottenham shirt he always played with his heart and spirit for the club and gave everything, and everyone appreciates his efforts here.
"He certainly will be a legend at the club."
Sherwood also revealed that midfielder Sandro is back in contention for the clash with Dnipro - that will see Tottenham attempting to overturn a 1-0 deficit at White Hart Lane - after missing the past two months with injury.
"We've been very careful with Sandro because he's been out for long periods and, previously, when he's been put back in too early he's had a little niggle and he's had to miss a few weeks," the manager added. "But he's done more training than he's ever done before so we've strengthened the injury and we're hoping that he's ready to go.
"It's good to have Sandro back in the squad. He's a great character around the dressing room and he gives everything on the pitch and leaves nothing on the field. You know for sure he's going to give you 100 percent."