Flightless New Zealand bird (4)
I believe the answer is:
kiwi
'flightless new zealand bird' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for kiwi that I've seen before include "Rutherford was one" , "Symbol of New Zealand" , "New Zealander (informal)" , "Someone from Auckland?" , "Hairy fruit with green flesh" .)