Not prepared for revolution, or major conflict (3)
I believe the answer is:
war
'major conflict' is the definition.
(a war is a major outbreak of fighting)
'not prepared for revolution' is the wordplay.
'not prepared' becomes 'raw' (as in raw food).
'for revolution' says the letters should be written backwards (letters revolve back).
'raw' reversed gives 'WAR'.
'or' is the link.
(Other definitions for war that I've seen before include "Major conflict" , "Large-scale conflict" , "Hostile situation" , "Sustained conflict" , "Fight" .)