Underground force in Scottish city (10)

I believe the answer is:

metropolis

'city' is the definition.
('metropolis' can be a synonym of 'city')

'underground force in scottish' is the wordplay.
'underground' becomes 'metro' ('metro' can be a synonym of 'underground').
'force in scottish' becomes 'polis' (Scottish dialect term for 'police').
'metro'+'polis'='METROPOLIS'

(Other definitions for metropolis that I've seen before include "London, say" , "Big city" , "Expressionist movie" , "Urban centre" , "See" .)

I've seen this clue in The Independent.

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