Violent players may be plastered (9)
I believe the answer is:
roughcast
'may be plastered' is the definition.
(I've seen this before)
'violent players' is the wordplay.
'violent' becomes 'rough'.
'players' becomes 'cast' (I've seen this before).
'rough'+'cast'='ROUGHCAST'
(Other definitions for roughcast that I've seen before include "outdoor coat" , "Lacking refinement" , "Superficial application" , "not in the best of form yet" , "Pebbled surface of wall" .)