A supportive fellow? (3)
I believe the answer is:
guy
'fellow?' is the definition.
(both can mean a man)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for guy that I've seen before include "Ridicule like Fawkes" , "One burned on Nov. fifth" , "Rope; man's name" , "send up?" , "Cable, wire etc used to brace something" .)