Plot maid concocted as go-between (8)
I believe the answer is:
diplomat
'go-between' is the definition.
(diplomat is a kind of go-between)
'plot maid concocted' is the wordplay.
'concocted' indicates anagramming the letters.
'plot'+'maid'='plotmaid'
'plotmaid' anagrammed gives 'DIPLOMAT'.
'as' is the link.
(Other definitions for diplomat that I've seen before include "Limp toad (anag.)" , "Tactful person, maybe in public service" , "Official such as an ambassador" , "envoy, say" , "National representative abroad" .)