100 sheets of paper, off-white (5)
I believe the answer is:
cream
'off-white' is the definition.
(similar colours)
'100 sheets of paper' is the wordplay.
'100' becomes 'C' (Roman numeral).
'sheets of paper' becomes 'ream' (a ream is a large amount of paper).
'c'+'ream'='CREAM'
(Other definitions for cream that I've seen before include "Butterfat part of milk" , "Very best; pale yellow" , "Fat-rich part of milk" , "Dairy product" , "Thick milk" .)