Utter brute, for a fighter (8)

I believe the answer is:
guerilla
'a fighter' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'utter brute' is the wordplay.
'utter' shows a homophone (sound like) (I've seen 'uttered' mean this).
'brute' becomes 'gorilla' (gorilla can mean a brutish person).
'gorilla' sounds like 'GUERILLA'.
'for' is the link.
Can you help me to learn more?
(Other definitions for guerilla that I've seen before include "He fights as part of small independent group" , "partisan" , "Freedom fighter" , "One of small independent group of fighters" , "Insurgent who works through sabotage and harassment" .)
