Revenge (8)
I believe the answer is:
reprisal
'revenge' is the definition.
(I know that reprisal is a type of revenge)
This is the entire clue.
(Other definitions for reprisal that I've seen before include "Act of retaliation or vengeance" , "Retaliation for an injury" , "Retaliatory action against an enemy" , "comeback" , "Tit for tat" .)