The loan goes for fuel (7)
I believe the answer is:
ethanol
'fuel' is the definition.
The answer and definition can be both substances as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'the loan goes' is the wordplay.
'goes' is an anagram indicator (I've seen 'went' mean this ('go' can mean move)).
'the'+'loan'='theloan'
'theloan' with letters rearranged gives 'ETHANOL'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for ethanol that I've seen before include "volatile flammable substance" , "Form of alcohol" , "spirit" , "Ethyl alcohol" , "Intoxicant in wine, spirits, etc" .)