Wicked material that is made light of! (6)
I believe the answer is:
tallow
This could be a double definition.
'wicked material' is the first definition.
The answer and definition can be both substances as well as being singular nouns.
Maybe there's an association between them I don't understand?
'made light of' is the second definition.
The definition suggests a singular noun which matches the answer.
'that is' is the link.
Can you help me to learn more?
(Other definitions for tallow that I've seen before include "Animal fat used to make ..." , "Candle wax" , "Melted, clarified animal fat" , "Outstanding entertainer" , "Fat processed for making candles" .)