King Duncan's killer (7)
I believe the answer is:
macbeth
'king duncan's killer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for macbeth that I've seen before include "Ill-fated Shakespearean king" , "Shakespearean play" , "dramatic role" , "Shakespearean tragedy" , "bloody drama" .)