Glib talk by northern model (7)
I believe the answer is:
pattern
'model' is the definition.
(I know that pattern is a type of model)
'glib talk by northern' is the wordplay.
'glib talk' becomes 'patter' (I've seen this in another clue).
'by' is a charade indicator (letters next to each other).
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'patter'+'n'='PATTERN'
(Other definitions for pattern that I've seen before include "Repeated decorative design" , "Model or design from which to make clothes, say" , "Shape or design" , "Model to imitate" , "Design for copying" .)