Inexperienced revolutionary in conflict (3)
I believe the answer is:
war
'conflict' is the definition.
(war is a kind of conflict)
'inexperienced revolutionary' is the wordplay.
'inexperienced' becomes 'raw' (similar in meaning).
'revolutionary' is a reversal indicator (letters revolve around).
'raw' reversed gives 'WAR'.
'in' is the link.
(Other definitions for war that I've seen before include "State of armed struggle" , "Fight" , "Battle" , "Sustained conflict" , "Strife" .)