Of the sea or seafaring (8)
I believe the answer is:
maritime
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">of the sea</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">seafaring</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for maritime that I've seen before include "Naval" , "Bordering on the sea" , "Found near the sea" , "Connected to the sea and sea-faring" , "Nautical" .)