If he is getting around he should be fine. I don't know if there is a cure or not. Maybe someone else will know. But I wanted to let you know that we have a hen with a club foot (we affectionately call her Clubby) and she gets around just as good as the others. Don't know how old she is we are guessing around 7. I hope this helps calms your fears a little.
what exactly do you mean by "club" foot? Are the toes are curled up? Are the legs spraddled? If only curly toes then you can try three drops of polyvisol once a day for a week into beak and then taper off the next as curled-toe paralysis is often helped by giving the B vitmain specifically assoc with this... also tape the foot in the proper shape by making a shoe for it.