Expert marksman (12)
I believe the answer is:
sharpshooter
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">expert marksman</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for sharpshooter that I've seen before include "Expert marksman" , "I'm very good at firing" , "skilled marksman" , "Gunman" , "Someone with gun" .)