Ship carrying crude oil (6)
I believe the answer is:
tanker
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ship carrying crude oil</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 tanker that I've seen before include "Ship or vehicle to carry crude oil" , "Ship or lorry containing oil" , "'Ship, carrying crude oil say (6)'" , "Petrol transporter" , "Large cargo ship" .)