Clarke felt he had ‘unfinished business’ with the Saddlers and wanted to stay but was let go this month after two years at the club.
In his final months at Walsall he saw Leak emerge and get his chance and Clarke believes the 20-year-old has what it takes to forge a successful career.
“He can go all the way,” Clarke said.
“Trying to play well in a poor side at that age, I can’t talk any higher of him.
“He trains well every day and wears his heart on his sleeve. He’s in the gym, does everything right. There’s no reason why he shouldn’t be able to have a half decent career. Credit to him, he listens and learns. Everyone has worked with him and it’s showing because the ones that don’t listen fall away. He’s dedicated himself 100 per cent to football and it’s shown.
“He’s a lovely guy and can hold an in-depth conversation – not many young lads can nowadays!
“He’s always in the gym and always asking questions, which I think is class. If he’s not sure on something he’ll ask and you need that if you want to learn. You can’t go through the learning process not asking questions.”