Clayton impressed during his loan spell with United last term.
"At the minute Adam is away in Mexico but I have spoken to him and his agent all summer," the United boss told the News & Star. "He has spoken in the press about fighting for his Man City place and getting into their team.
"If that changes we would be daft not to make him an offer. We will decide what to do based on what happens with him at Man City in pre-season."