Birdie -- another one better? (5)
I believe the answer is:
eagle
'birdie another one better?' is the definition.
(two under par in golf)
This is the entire clue.
(Other definitions for eagle that I've seen before include "King of birds" , "A glee-ful bird?" , "two strokes fewer?" , "Flyer" , "Score of two strokes under par for a golf hole" .)