Assuming the returning players, or at least some of them, stay fit then a winger, some one like Aaron Lennon (who I know has had his personal issues).
I mentioned Jack Colback recently who still isn't getting a game at Newcastle. Not sure he'd come south though as he turned down moves to Wolves and Hull in the summer on those grounds. He's 28 with plenty of experience in the top flight and would be a great asset.