Hope a tanker contains fuel (4)
I believe the answer is:
peat
'fuel' is the definition.
(peat is a kind of fuel)
'hope a tanker contains' is the wordplay.
'contains' says the answer is hidden in the clue.
'PEAT' is hidden in the letters of 'hope a tanker'.
(Other definitions for peat that I've seen before include "Partially carbonised vegetable matter used as a fuel when dried" , "Tape around turf" , "Dried plant material used as fuel" , "Fuel cut from bog" , "Fuel or compost (but no longer to be used as such!)" .)