First supplement you should consider is food. Eat lots of protein (meat, fish, nuts, whatever).
Next stuff that has evidence to support sparing of muscle tissue during trauma is glutamine (research is in patients with serious trauma, I.e. car accidents and cancer), but...
Next is something less clear like cissus quadrangularis. Eastern medicine loves this and it has ben shown to heal fractures in dogs much faster than controls... I bought some for my bro who had an ACL reconstruction (second one) and he aaid it made a big difference... whatever that is worth.
None of this stuff will ave your 'definition', which is itself a rubbish term for low localised bodyfat combined with muscle perfusion... the only thing that will save that is using those muscles.