Go with commanding officer and arrest gutless traitor (8)
I believe the answer is:
turncoat
'traitor' is the definition.
(thesaurus)
'go with commanding officer and arrest gutless' is the wordplay.
'go with' becomes 'turn' ('turn' can be a synonym of 'go'. I am not sure about the 'with' bit.**).
'commanding officer' becomes 'co'.
'and' is a charade indicator (letters next to each other).
'gutless' says to hollow out the word (remove centre letters).
'arrest' with its middle removed is 'at'.
'turn'+'co'+'at'='TURNCOAT'
Can you help me to learn more?
(Other definitions for turncoat that I've seen before include "Traitor with reversed garment" , "Traitor, defector" , "Traitor with inverted garment" , "treacherous as one?" , "Judas" .)