Flightless bird of South America (4)
I believe the answer is:
rhea
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">flightless bird of south america</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for rhea that I've seen before include "Large flightless bird" , "Fertility goddess in ancient Greek mythology" , "Flightless bird from South America" , "Titaness" , "Fast runner" .)