Talk about a northern dog (7)
I believe the answer is:
spaniel
'dog' is the definition.
(I know that spaniel is a type of hunting dog)
'talk about a northern' is the wordplay.
'talk' becomes 'spiel' (spiel can mean a sales pitch or talk).
'about' is an insertion indicator.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'a'+'n'='an'
'spiel' placed around 'an' is 'SPANIEL'.
(Other definitions for spaniel that I've seen before include "Dog with long silky coat" , "Droopy-eared dog" , "See 13" , "Gundog; obsequious type" , "Kind of dog, may be a cocker" .)