King Duncan's killer (7)
I believe the answer is:
macbeth
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">king duncan's killer</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 macbeth that I've seen before include "Ill-fated Shakespearean king" , "Shakespearean play" , "dramatic role" , "Shakespearean tragedy" , "bloody drama" .)