A rest home dished up food British wouldn't want? (9)
I believe the answer is:
horsemeat
'food british wouldn't want?' is the definition.
'a rest home dished up' is the wordplay.
'dished up' is an anagram indicator.
'a'+'rest'+'home'='aresthome'
'aresthome' anagrammed gives 'HORSEMEAT'.
(Other definitions for horsemeat that I've seen before include "source of food adulteration?" , "It's not served in most restaurants!" , "food fit for dogs" .)