Petroleum product (8)
I believe the answer is:
paraffin
'petroleum product' is the definition.
(I know that paraffin is a type of petroleum product)
This is all the clue.
(Other definitions for paraffin that I've seen before include "Flammable wax" , "Possibly oil" , "Kerosene" , "Waxy flammable substance" , "Liquid fuel" .)