Colour of many a quantity of paper (5)
I believe the answer is:
cream
'colour of' is the definition.
The answer and definition can be both groups as well as being singular nouns.
Maybe there's an association between them I don't understand?
'many a quantity of paper' is the wordplay.
'many' becomes 'c' (C is the Roman numeral for 100).
'a quantity of paper' becomes 'ream' (a ream is a large amount of paper).
'c'+'ream'='CREAM'
Can you help me to learn more?
(Other definitions for cream that I've seen before include "treat for cat?" , "Dairy product" , "Beat" , "'There are more ways of killing a cat than choking it with ....." , "Butterfat part of milk" .)