Military campaign award uncovered (3)
I believe the answer is:
war
'military' is the definition.
(relating to war or the military)
'campaign award uncovered' is the wordplay.
'uncovered' says the answer is hidden in the clue.
'WAR' is hidden in the letters of 'campaign award'.
(Other definitions for war that I've seen before include "Major conflict" , "Large-scale conflict" , "Combat" , "Open hostility" , "State of armed conflict" .)