Smear ruined lots of papers (5)
I believe the answer is:
reams
'lots of papers' is the definition.
'reams' can be an answer for 'papers' (a ream is a large amount of paper). I'm not sure about the 'lots of' bit.
'smear ruined' is the wordplay.
'ruined' indicates anagramming the letters.
'smear' with letters rearranged gives 'REAMS'.
Can you help me to learn more?
(Other definitions for reams that I've seen before include "Large quantity of written matter" , "Lots of paper" , "Scrapes the barrel" , "a very large amount" , "This much paperwork" .)