Hughes worked with Dempsey at Fulham.
"If players want to move, they can instigate moves," Hughes said when asked about Dempsey.
"That seems to have been the case but I am not privy to the details.
"In the end, Fulham ideally I imagine would have liked to keep him.
"Sometimes you have to accept that the player wants to move on and at that point you have to make sure you get the best deal for your club and I am sure that is what Fulham did.
"Clint is a very single-minded young man and he is a guy that is very, very driven.
"He wants to progress in his career and he does everything to that end.
"He works exceptionally hard in training, had an outstanding season obviously when I was manager and probably topped that with the amount of goals he scored for Fulham last year.
"You probably felt it was the right time for him to move. He was at the peak of his powers and he wanted to move on to pastures new.
"It was a little bit of a surprise that he ended up at Spurs because there was a lot of talk he would go elsewhere."