Killing of one's mother (9)
I believe the answer is:
matricide
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">killing of one's mother</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for matricide that I've seen before include "Killer" , "Murder of one's mother" , "Murderer" , "The killing of one's mother" , "Diametric killing of a mother" .)