Large Australian flightless bird (3)
I believe the answer is:
emu
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">large australian flightless bird</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for emu that I've seen before include "Australian non-flyer" , "Large Australian flightless bird" , "Fast runner in Oz" , "Australian bird related to the ostrich" , "Big bird" .)