Helsinki resident, perhaps, fine in north (4)
I believe the answer is:
finn
'helsinki resident' is the definition.
(I've seen this in another clue)
'fine in north' is the wordplay.
'fine' becomes 'f' (abbreviation in pencil classifications).
'north' becomes 'N' (abbreviation).
'f'+'in'+'n'='FINN'
'perhaps' is the link.
(Other definitions for finn that I've seen before include "Sibelius, perhaps" , "EU statesman" , "Northern European" , "National" , "Eg, Helsinki native" .)