Fuel in ground, first to come out (3)
I believe the answer is:
oil
'fuel' is the definition.
(thesaurus)
'ground first to come out' is the wordplay.
'ground' becomes 'soil' (soil is a kind of ground).
'first to come out' means to remove the first letter.
'soil' with its first letter taken away is 'OIL'.
'in' acts as a link.
(Other definitions for oil that I've seen before include "Type of fuel" , "Fuel, lubricant" , "painting" , "Black gold" , "Liquid gold" .)