Unprepared for war breaking out (3)
I believe the answer is:
raw
'unprepared' is the definition.
(I've seen this in another clue)
'war breaking out' is the wordplay.
'breaking out' indicates an anagram.
'war' anagrammed gives 'RAW'.
'for' acts as a link.
(Other definitions for raw that I've seen before include "Not prepared" , "Uncooked; immature" , "Abraded" , "not manufactured" , "Uncooked or unsavoury" .)