Songbird — it goes after seed (5)
I believe the answer is:
pipit
'songbird' is the definition.
(I've seen this before)
'it goes after seed' is the wordplay.
'goes after' is a charade indicator (letters next to each other).
'seed' becomes 'pip' (I've seen this before).
'it' after 'pip' is 'PIPIT'.
(Other definitions for pipit that I've seen before include "Singer" , "Small bird of rock or meadow" , "Bird related to wagtail" , "Bird of meadow, tree, or rock" , "Ground-dwelling songbird" .)