Bird pecked another (7)
I believe the answer is:
bittern
'bird' is the definition.
(bittern is a kind of bird)
'pecked another' is the wordplay.
'pecked' becomes 'bit' (I've seen this in other clues).
'another' becomes 'tern' (I can't explain this - if you can you should give a lot more credence to this answer).
'bit'+'tern'='BITTERN'
Can you help me to learn more?
(Other definitions for bittern that I've seen before include "Bird of marshes" , "'He shall not hear the . . . cry' (Ledwidge)" , "Marsh bird of the heron family" , "Booming marsh bird" , "inhabitant of marsh" .)