Old society girl with mad somersaulting seriously injured? (7)
I believe the answer is:
stabbed
'seriously injured?' is the definition.
(to stab someone is to seriously injure them)
'old society girl with mad somersaulting' is the wordplay.
'old society girl' becomes 'deb' (debutante).
'with' is a charade indicator (letters next to each other).
'mad' becomes 'bats' (informal term for mad).
'somersaulting' says the letters should be written backwards (letters flip or somersault over).
'deb'+'bats'='debbats'
'debbats' in reverse letter order is 'STABBED'.
(Other definitions for stabbed that I've seen before include "assaulted" , "Penetrated with e.g. dagger" , "Attacked" , "Pierced with a dagger" , "Wounded with a knife" .)