Ship's commander (7)
I believe the answer is:
captain
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ship's commander</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 captain that I've seen before include "Head of a ship's crew" , "Is Pat Cain in charge of the ship?" , "Naval rank" , "US policeman" , "American police officer" .)