Decapitate (6)
I believe the answer is:
behead
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">decapitate</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for behead that I've seen before include "Remove cranium as in old execution" , "Guillotine" , "Carry out execution" , "Top" , "Remove the crown" .)