Clarke is willing to sell Graham Dorrans and replace him with Thorne.
He said: "I've got a replacement, I've got George Thorne back. His loan spell has helped him a lot and he did very well at Old Trafford.
"Even when he came into the game (against Fulham) the other day, he showed that he has improved. We got some great reports from Peterborough. It was just what the boy needed.
"He needed regular football. We're grateful to Peterborough for giving him the chance to have that. I've always known he has big potential."