Hit over the head? (4)
I believe the answer is:
cosh
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hit over 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 cosh that I've seen before include "Blackjack" , "Heavy stick-like weapon" , "From this, blow" , "Personal weapon" , "Club used as a weapon" .)