Extremely rude over a meal (6)
I believe the answer is:
repast
'a meal' is the definition.
(synonyms)
'extremely rude over' is the wordplay.
'extremely' suggests removing the centre (only the extremes of the word are used).
'over' becomes 'past' (I've seen this before).
'rude' with its middle removed is 're'.
're'+'past'='REPAST'
(Other definitions for repast that I've seen before include "A formal sort of meal" , "lunch?" , "Something to eat" , "Feast, meal" , "Food - tapers (anag)" .)