Bird unable to fly, somewhat bemused (3)
I believe the answer is:
emu
'bird unable to fly' is the definition.
(flightless bird)
'somewhat bemused' is the wordplay.
'somewhat' indicates the answer is hidden within the clue.
'EMU' can be found hidden inside 'bemused'.
(Other definitions for emu that I've seen before include "Ostrich-like bird" , "Big bird" , "Australian non-flyer" , "Aussie bird" , "Australian running bird." .)