“Get lost!” mutinous paper said (9)
I believe the answer is:
disappear
'get lost' is the definition.
(I've seen this before)
'mutinous paper said' is the wordplay.
'mutinous' indicates anagramming the letters.
'paper'+'said'='papersaid'
'papersaid' is an anagram of 'DISAPPEAR'.
(Other definitions for disappear that I've seen before include "Vanish from view" , "Melt away" , "Escape" , "Fade out" , "Pass out of sight" .)