Wicked act (8)
I believe the answer is:
atrocity
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">wicked act</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for atrocity that I've seen before include "Frightful act of citatory kind" , "Wickedness" , "monstrous crime" , "Barbarous, inhuman act" , "Barbarity, inhumanity" .)