Privateer (7)
I believe the answer is:
corsair
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">privateer</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 corsair that I've seen before include "Marauder" , "Barbary pirate - pirate ship" , "Buccaneer" , "Seafarer" , "20 across" .)