Keep quiet on Socialist scrap (5)
I believe the answer is:
shred
'scrap' is the definition.
(thesaurus)
'keep quiet on socialist' is the wordplay.
'keep quiet' becomes 'sh'.
'on' says to put letters next to each other.
'socialist' becomes 'red' (red is a kind of socialist).
'sh'+'red'='SHRED'
(Other definitions for shred that I've seen before include "Thin scrap or strip" , "Torn strip of cloth" , "just a touch" , "(Reduce to) small piece(s)" , "Tear into tiny pieces" .)