City subway not quite European (10)
I believe the answer is:
metropolis
'city' is the definition.
(I know that city can be written as metropolis)
'subway not quite european' is the wordplay.
'subway' becomes 'metro' (synonyms).
'not quite' means to remove the last letter (most but not all of the word).
'european' becomes 'polish' (Poland is in Europe).
'polish' with its final letter removed is 'polis'.
'metro'+'polis'='METROPOLIS'
(Other definitions for metropolis that I've seen before include "See" , "Big city" , "centre of activity" , "early film" , "Urban centre" .)