Good score for a bird (5)
I believe the answer is:
eagle
I believe this is a double definition.
'good score' is the first definition.
(I've seen this before)
'bird' is the second definition.
(eagle is a type of bird)
'for a' acts as a link.
(Other definitions for eagle that I've seen before include "somewhat under par" , "The bald one is a US symbol" , "Symbolic American bird" , "It may soar" , "King of birds" .)