Cleaner fuel as drawing material (8)
I believe the answer is:
charcoal
'drawing material' is the definition.
(I've seen this before)
'cleaner fuel' is the wordplay.
'cleaner' becomes 'char' (char can mean a cleaner).
'fuel' becomes 'coal' (coal is a kind of fuel).
'char'+'coal'='CHARCOAL'
'as' acts as a link.
(Other definitions for charcoal that I've seen before include "Fuel - stick for drawing" , "coloured sticks" , "Art material and fuel" , "Fuel for barbecue cookers" , "type of fuel" .)