Leaders of radical avant garde slated in tabloids (4)
I believe the answer is:
rags
'tabloids' is the definition.
('rag' can be a synonym of 'tabloid')
'leaders of radical avant garde slated' is the wordplay.
'leaders of' says to take the initial letters.
The first letters of 'radical avant garde slated' is 'RAGS'.
'in' is the link.
(Other definitions for rags that I've seen before include "Pieces of old cloth" , "tabloids" , "kids" , "Papers" , "Small pieces of cloth (but can be glad)" .)