Ship carrying crude oil (6)
I believe the answer is:
tanker
'ship carrying crude oil' is the definition.
(I've seen this before)
This is the entire clue.
(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" .)