Not the first transaction concerning a northern town (6)

I believe the answer is:

resale

I'm a little stuck... Click here to teach me more about this clue!

'not the first transaction' is the definition.
(I've seen this in another clue)

'concerning a northern town' is the wordplay.
'concerning' becomes 're' (both can mean on a particular topic).
'a northern town' becomes 'sale' (I can't justify this - if you can you should believe this answer much more).
're'+'sale'='RESALE'

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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