Favourite part of Morpeth (3)
I believe the answer is:
pet
'favourite' is the definition.
(synonyms)
'part of morpeth' is the wordplay.
'part of' indicates a hidden word.
'PET' is hidden in the letters of 'morpeth'.
(Other definitions for pet that I've seen before include "Tame animal kept for companionship" , "Favourite, perhaps a domestic animal" , "Little darling" , "Cherished animal" , "House animal; sulk" .)