Blocks of paper are wasted on manuscript (5)
I believe the answer is:
reams
'blocks of paper' is the definition.
I know that 'paper' relates to this answer. I also know that both the answer and definition are plural nouns
'are wasted on manuscript' is the wordplay.
'wasted' indicates anagramming the letters.
'on' is a charade indicator (letters next to each other).
'manuscript' becomes 'ms' (abbreviation for manuscript).
'are' anagrammed gives 'rea'.
'rea'+'ms'='REAMS'
Can you help me to learn more?
(Other definitions for reams that I've seen before include "This much paperwork" , "Large quantities (of paper?)" , "Scrapes the barrel" , "a very large amount" , "Large quantity of written matter" .)