The topic pretty much says it all. What if Clark - be it as himself, or Superman, or Kal-El - lost a limb during some kind of accident?
First of all, such an accident would have to either involve kryptonite and something else (blunt force? a cutting edge?) to cost Clark a limb. Or it would have to happen on New Krypton.
I imagine that it would be pretty awkward for Clark to have to make do with only one hand, but I can sure see him having only one complete leg, for example.
How would Clark deal with the issues of not having a whole body any more? Of being "crippled"? Would he use a prothesis? (Maybe even a Kryptonian one? Or one designed by Doc Klein?) And how would Clark cope with his dual identity?