Hide fuel before fabric (7)
I believe the answer is:
oilskin
'fabric' is the definition.
(I have seen 'Waterproof fabric' mean 'oilskin' so perhaps 'fabric' could also mean 'oilskin')
'hide fuel before' is the wordplay.
'hide' becomes 'skin' (synonyms).
'fuel' becomes 'oil' (I've seen this before).
'before' means one lot of letters go next to another.
'skin' after 'oil' is 'OILSKIN'.
(Other definitions for oilskin that I've seen before include "Heavy-duty waterproof" , "Waterproof cloth as for sailors" , "material" , "security for a rainy day" , "protective cloth" .)