Ostrich's kin (3)
I believe the answer is:
emu
'ostrich's kin' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for emu that I've seen before include "Large Australian flightless bird" , "unit of measurement" , "Australian bird related to the ostrich" , "it can't get off the ground" , "Long-necked bird" .)