Raven-keeper brings grouse to diner (9)
I believe the answer is:
beefeater
'raven-keeper' is the definition.
(Tower of London Beefeaters keep ravens)
'grouse to diner' is the wordplay.
'grouse' becomes 'beef' (synonyms).
'to diner' becomes 'eater' (to dine is to eat a meal).
'beef'+'eater'='BEEFEATER'
'brings' is the link.
(Other definitions for beefeater that I've seen before include "Yeoman of the Guard; carnivore" , "One might guard" , "Tower of London guard" , "Royal servant" , "no vegetarian?" .)