County Tipperary has an old city with new economic problem (8)

I believe the answer is:

downturn

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'economic problem' is the definition.
The definition suggests a singular noun which matches the answer.

'county tipperary has an old city with new' is the wordplay.
'county' becomes 'down' (County Down in Northern Ireland).
'tipperary has' becomes 't' (I can't justify this - if you can you should believe this answer much more).
'an old city' becomes 'ur' (ancient city state).
'with' says to put letters next to each other.
'new' becomes 'n'.
'down'+'t'+'ur'+'n'='DOWNTURN'

Can you help me to learn more?

(Other definitions for downturn that I've seen before include "Worsening of economic activity" , "Decline in business" , "Drop" , "Decline eg of economic activity" , "Reduction in business" .)

I've seen this clue in the Irish Times and the Irish Times (Crosaire).

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