Towing vessel (7)
I believe the answer is:
tugboat
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">towing vessel</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for tugboat that I've seen before include "Drawing craft" , "Vessel drawing" , "Ship pulling a larger one" , "Vessel towing larger vessels" , "Harbour craft" .)