Perhaps salver coated in ale and grass (8)
I believe the answer is:
betrayer
'grass' is the definition.
(I've seen this before)
'perhaps salver coated in ale' is the wordplay.
'perhaps salver' becomes 'tray'.
'coated in' is an insertion indicator.
'ale' becomes 'beer' (I've seen this before).
'tray' placed inside 'beer' is 'BETRAYER'.
'and' acts as a link.
(Other definitions for betrayer that I've seen before include "snake" , "One who is treacherous" , "traitor" , "Eg Judas Iscariot" , "rat" .)