Extinct NZ bird (3)
I believe the answer is:
moa
'extinct nz bird' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for moa that I've seen before include "Extinct flightless bird of New Zealand" , "bird that became extinct" , "Flightless bird once found in New Zealand" , "Bird's gone for ever" , "Bird no longer" .)