Small firm with employment for northerner (6)
I believe the answer is:
scouse
'northerner' is the definition.
(I've seen this before)
'small firm with employment' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'firm' becomes 'co' (a firm is a company).
'with' is a charade indicator (letters next to each other).
'employment' becomes 'use' (how something is used).
's'+'co'+'use'='SCOUSE'
'for' is the link.
(Other definitions for scouse that I've seen before include "Slang for native of Liverpool" , "What they speak in Liverpool?" , "English dialect spoken in Liverpool" , "Liverpudlian (colloq.)" , "another city's dialect" .)