Associate, confederate (4)
I believe the answer is:
ally
This clue is a double definition.
'associate' is the first definition.
(ally is a kind of associate)
'confederate' is the second definition.
(synonyms)
(Other definitions for ally that I've seen before include "Colleague, confederate" , "Supporter in a conflict" , "Friend and colleague" , "State formally cooperating with another" , "Friend, partner" .)