Feathered friend one under par (6)
I believe the answer is:
birdie
I believe this is a double definition.
'feathered friend' is the first definition.
(I've seen this in another clue)
'one under par' is the second definition.
(I've seen this in another clue)
(Other definitions for birdie that I've seen before include "Golfing score better than par" , "One watched" , "One under par - watch it!" , "Golf score of one stroke under par" , "low score" .)