Betrayer of the Moor (4)
I believe the answer is:
iago
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">betrayer of the moor</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 iago that I've seen before include "Evil character in Othello" , "Organ stop" , "villain in play" , "villainous ensign" , "Othello's evil counsellor" .)