Hit with the head (4)
I believe the answer is:
butt
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hit with the head</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 butt that I've seen before include "Large cask" , "Fag-end" , "Use your head aggressively" , "What goat may do" , "Scapegoat - strike - bottom - barrel" .)