Conservative has drink and favourite muffin (7)
I believe the answer is:
crumpet
'muffin' is the definition.
(I've seen this before)
'conservative has drink and favourite' is the wordplay.
'conservative' becomes 'C' (UK political abbreviation).
'has' is a charade indicator (letters next to each other).
'drink' becomes 'rum' (rum is a kind of drink).
'and' is a charade indicator (letters next to each other).
'favourite' becomes 'pet' (synonyms).
'c'+'rum'+'pet'='CRUMPET'
(Other definitions for crumpet that I've seen before include "Muffin" , "Thick flat cake, eaten toasted" , "Toasted teacake" , "Thick soft cake eaten toasted and buttered" , "Round yeast cake eaten hot with butter" .)