Sweet stuff made rare in mixture (8)
I believe the answer is:
demerara
'mixture' is the definition.
The answer and definition can be both substances as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'sweet stuff made rare in' is the wordplay.
'sweet' becomes 'era' (I can't explain this - if you can you should give a lot more credence to this answer).
'stuff' is an anagram indicator (I've seen 'stuffed' mean this).
'rare' becomes 'r' (listed by Oxford Dictionary of Abbreviations).
'in' indicates putting letters inside.
'made'+'r'='mader'
'mader' anagrammed gives 'demra'.
'era' put inside 'demra' is 'DEMERARA'.
Can you help me to learn more?
(Other definitions for demerara that I've seen before include "sweetener" , "Type of brown sugar" , "Sweet thing" , "sugar - and alcohol" , "Light brown cane sugar" .)