Cleopatra's nemesis (3)
I believe the answer is:
asp
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cleopatra's nemesis</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 asp that I've seen before include "Snake of the Nile" , "Cleopatra's poisoner" , "creeper" , "Snake found in spa" , "Small poisonous snake" .)