The player was told by (SAFC) to closed down his Twitter page earlier this week after getting embroiled in a bizarre dispute surrounding his IRA links.
Martin O'Neill: "I think he now feels that concentrating totally on football issues is the most important thing for him.
"He had a whirlwind start and by his own admission, he's finding the second season difficult.
"Sometimes when you are tweeting, you might feel as if you're speaking to three or four friends.
"But this is for public consumption. I think he realises the best thing is to leave things alone and concentrate on footballing issues.
"That's very important in a game which can be excellent for you. But if you take your eye off the ball, you can disappear very, very quickly.
"He was flying from January to the end of the season and the thought was 'I will just continue on' but you have to knuckle down.
"He came back here and has not hit the same form. I still believe if he clears his head and starts to concentrate on the game he can get back to where he was."
O'Neill confirmed that he would not be fining McClean for making a brief return to Twitter against club orders.
"I'll deal with things internally, but he hasn't been fined."