Bird in poem, unusual (3)
I believe the answer is:
emu
'bird' is the definition.
(emu is a kind of bird)
'in poem unusual' is the wordplay.
'in' indicates a hidden word.
'EMU' is hidden in the letters of 'poem unusual'.
(Other definitions for emu that I've seen before include "Big bird" , "Ostrich-like bird" , "it can't get off the ground" , "Bird of tremulous kind" , "Aussie bird" .)