Aussie runner (3)
I believe the answer is:
emu
'aussie runner' is the definition.
(Australian bird that runs)
This is all the clue.
(Other definitions for emu that I've seen before include "that doesn't get off the ground" , "Large Australian flightless bird" , "Long-necked bird" , "Australian non-flyer" , "Flightless bird of Australia, like ostrich" .)