Town or new city (9)
I believe the answer is:
rochester
'town' is the definition.
(I've seen this before)
'or new city' is the wordplay.
'new' indicates anagramming the letters.
'city' becomes 'chester' (Chester is an example).
'or' is an anagram of 'ro'.
'ro'+'chester'='ROCHESTER'
(Other definitions for rochester that I've seen before include "Kentish Town" , "Novel hero" , "Madwoman's husband" , "One city" , "ancient port" .)