Sound of a gun (4)
I believe the answer is:
bang
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sound of a gun</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 bang that I've seen before include "Sudden loud noise like an explosion" , "Straight fringe of hair" , "Sudden noise; fringe" , "Gun sound" , "drug injection" .)