A tomb can't corrupt an adversary (9)
I believe the answer is:
combatant
'an adversary' is the definition.
(thesaurus)
'a tomb can't corrupt' is the wordplay.
'corrupt' indicates anagramming the letters (a corrupted spelling of the word).
'a'+'tomb'+'cant'='atombcant'
'atombcant' with letters rearranged gives 'COMBATANT'.
(Other definitions for combatant that I've seen before include "Soldier" , "one involved in fighting" , "Fighter" , "Belligerent" , "One engaged in fighting" .)