Bud ... or bait (4)
I believe the answer is:
chum
I believe this is a double definition.
'bud' is the first definition.
(I've seen this in another clue)
'bait' is the second definition.
(I know that chum is a type of bait)
(Other definitions for chum that I've seen before include "Pal, mate" , "Informally, a close friend" , "Good friend" , "Salmon" , "Pal, buddy" .)