European royal family has swamped Britain with revolting food (8)
I believe the answer is:
habsburg
'european royal family' is the definition.
(German royal dynasty)
'has swamped britain with revolting food' is the wordplay.
'swamped' means one lot of letters goes inside another (some letters are surrounded or swamped by others).
'britain' becomes 'B' (common abbreviation as in GB).
'with' is a charade indicator (letters next to each other).
'revolting' says the letters should be written backwards.
'food' becomes 'grub' (grub is a kind of food).
'grub' backwards is 'burg'.
'has' enclosing 'b' is 'habs'.
'habs'+'burg'='HABSBURG'
(Other definitions for habsburg that I've seen before include "Austrian imperial house" , "Dynasty" .)