Some beer not originally for bird (7)
I believe the answer is:
bittern
'bird' is the definition.
(bittern is a kind of bird)
'some beer not originally' is the wordplay.
'some beer' becomes 'bitter' (I've seen this before).
'originally' indicates taking the first letters.
The initial letter of 'not' is 'n'.
'bitter'+'n'='BITTERN'
'for' acts as a link.
(Other definitions for bittern that I've seen before include "Aquatic bird" , "Bird with a booming cry" , "''He shall not hear the ... cry / In the wild sky where he is lain'' (Lament for Thomas MacDonagh)" , "Bird of marshes" , "inhabitant of marsh" .)