Raise a glass to Queen Elizabeth’s kitchen assistant (7)
I believe the answer is:
toaster
'kitchen assistant' is the definition.
(kitchen appliance)
'raise a glass to queen elizabeth's' is the wordplay.
'raise a glass to' becomes 'toast' (to raise a glass to someone is to toast them).
'queen elizabeth' becomes 'ER' (abbreviation for Elizabeth Regina).
'toast'+'er'='TOASTER'
(Other definitions for toaster that I've seen before include "Bread griller" , "Person with role at wedding reception" , "Kitchen browner" , "Machine for making brown bread?" , "something in kitchen" .)