Unprepared, fighting back (3)
I believe the answer is:
raw
'unprepared' is the definition.
'fighting back' is the wordplay.
'fighting' becomes 'war'.
'back' is a reversal indicator.
'war' written backwards gives 'RAW'.
(Other definitions for raw that I've seen before include "Not cooked" , "Abraded" , "Not prepared" , "Uncooked or unsavoury" , "Naked" .)