Othello's betrayer (4)
I believe the answer is:
iago
'othello's betrayer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for iago that I've seen before include "Othello's enemy" , "Ancient role" , "stage villain" , "Othello's Ancient" , "Othello's ensign" .)