US city on way back after losing billions? Untrue (5)

I believe the answer is:

notso

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'losing billions? untrue' is the definition.
I know nothing about this answer so I cannot judge whether this works.

'us city on way back' is the wordplay.
'us city' becomes 'os' (I can't explain this - if you can you should believe this answer much more).
'on' becomes 'to'.
'way' becomes 'n' (Compass direction - North).
'back' shows that the letters should be reversed in order.
'os'+'to'+'n'='oston'
'oston' written backwards gives 'NOTSO'.

'after' is the link.

Can you help me to learn more?

I've seen this clue in The Irish Times.

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