Rum's not what the cure's made of (7)
I believe the answer is:
nostrum
'of' is the definition.
Both the definition and answer are singular nouns.
Perhaps there's an association between them I don't understand?
'rum's not what the cure's' is the wordplay.
'rum's not' anagrams to 'NOSTRUM'.
However, I am not sure how this is indicated.
'made' acts as a link.
Can you help me to learn more?
(Other definitions for nostrum that I've seen before include "Tonic" , "Some think it helps" , "Favourite remedy or scheme" , "secret potion" , "Hypothetical remedy for all ills" .)