Candle-fat (6)
I believe the answer is:
tallow
I believe this clue is a double definition.
'candle' is the first definition.
(thesaurus)
'fat' is the second definition.
(fat used to make candles)
(Other definitions for tallow that I've seen before include "burning fat" , "Animal fat used to make ..." , "Animal oil used in making soap and candles" , "Melted, clarified animal fat" , "Candle grease" .)