Ostrich's cousin (3)
I believe the answer is:
emu
'ostrich's cousin' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for emu that I've seen before include "Aussie bird" , "Ostrich-like bird" , "Flightless Aus. bird" , "that doesn't get off the ground" , "Aussie runner" .)