Aluminium company reversed order for fuel (4)
I believe the answer is:
coal
'for fuel' is the definition.
(coal is a kind of fuel)
'aluminium company reversed order' is the wordplay.
I cannot really understand how this works, but
'aluminium' could be 'al' (Al is the chemical symbol for aluminium) and 'al' is located in the answer.
'company' could be 'co' (abbreviation) and 'co' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for coal that I've seen before include "slack" , "This consists mainly of carbon" , "Solid fuel" , "Mined fuel" , "Char" .)