In difficulties, I owed for fuel (8)
I believe the answer is:
firewood
'fuel' is the definition.
(I know that firewood is a type of fuel)
'in difficulties i owed for' is the wordplay.
'i owed for' can be anagrammed to 'FIREWOOD'.
Though, I am not clear how this is indicated.
Can you help me to learn more?
(Other definitions for firewood that I've seen before include "Kindling for 17 across" , "Substance for burning" , "Tinder" , "Fuel from trees" , "Logs etc for fuel" .)