Battle suit (6)
I believe the answer is:
action
I believe this clue is a double definition.
'battle' is the first definition.
(military action)
'suit' is the second definition.
(synonyms)
(Other definitions for action that I've seen before include "Thing done; armed conflict" , "Order to start shooting" , "skirmish" , "Court case" , "Battle (in the law courts?)" .)