Rhea's relative (3)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rhea's relative</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for emu that I've seen before include "it can't get off the ground" , "Ostrich-like bird" , "Native Australian bird" , "Australian bird related to the ostrich" , "Fast runner in Oz" .)