Prelude to a duel
I believe the answer is:
slap
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">prelude to a duel</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for slap that I've seen before include "Cuff" , "Strike (in the face)" , "Strike action" , "Blow with open hand" , "Mild punishment" .)