"This club took him back from Man United when things weren't going so well and put their money where their mouth is to bring him back," said Pardew to the Croydon Advertiser.
"He's done great for me but I think there's improvement in him. I do think he's got some improvements to make to be a top player.
"I think we're a good platform for him to do that in the Premier League. I have tried to say to him I want him to be a massive success here.
"If Spurs blew us out of the water or Man City offered £50m and it was Champions League football, OK, it's because you're the finished product.
"This is what Wilf's ambition should be, but he needs to address his goals and assists.
"I don't think our fans would either. He knows he isn't there yet and he has no problem seeing that. I have told him that. Potentially, he could be."