City centre line (5)
I believe the answer is:
basel
'city' is the definition.
(Basel is an example)
'centre line' is the wordplay.
'centre' becomes 'base' (I have seen 'Centre of operations ' mean 'base' so perhaps 'centre' could also mean 'base').
'line' becomes 'l'.
'base'+'l'='BASEL'
(Other definitions for basel that I've seen before include "Swiss city" , "In European city" , "City of Switzerland" .)