Not allowed to consume fat (6)
I believe the answer is:
tallow
'fat' is the definition.
(fat used to make candles)
'not allowed to consume' is the wordplay.
'to consume' says the answer is hidden in the clue (I've seen 'consumes' mean this (the answer has been consumed by the clue)).
'TALLOW' is hidden in the letters of 'not allowed'.
(Other definitions for tallow that I've seen before include "Animal fat used in making soap" , "Candle, soap, fat" , "Candle ingredient" , "Melted, clarified animal fat" , "Outstanding entertainer" .)