Great - an awful singer (7)
I believe the answer is:
tanager
'singer' is the definition.
(tanager is a kind of birdanimal)
'great an awful' is the wordplay.
'awful' is an anagram indicator.
'great'+'an'='greatan'
'greatan' is an anagram of 'TANAGER'.
(Other definitions for tanager that I've seen before include "American songbird" , "South American singer" , "A bird" , "Songbird of the bunting family" .)