Mariner, seafarer (6)
I believe the answer is:
sailor
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">mariner</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">seafarer</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for sailor that I've seen before include "Jack" , "Tar, AB" , "Matelot" , "Sinbad, for example" , "One in the main" .)