Shakespearean villain (4)
I believe the answer is:
iago
'shakespearean villain' 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 "Evil character in Othello" , "stage villain" , "villainous ensign" , "Shakespearean villain" , "Advisor to soldier" .)