Large marine creature (9)
I believe the answer is:
swordfish
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">large marine creature</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 swordfish that I've seen before include "(Edible) long-snouted swimmer" , "Large marine creature" , "Marine creature with very long upper jaw" , "sea food" , "Xiphius gladius" .)