Foreign currency accepted by dodgy casinos in US city (3,9)
I believe the answer is:
san francisco
'us city' is the definition.
(I've seen this before)
'foreign currency accepted by dodgy casinos' is the wordplay.
'foreign currency' becomes 'franc' (former currency of France).
'accepted by' is an insertion indicator (inserted letters are accepted).
'dodgy' indicates an anagram (a dodgy or wrong order of the letters).
'casinos' anagrammed gives 'sanisco'.
'franc' going into 'sanisco' is 'SAN FRANCISCO'.
'in' is the link.
(Other definitions for san francisco that I've seen before include "Nineteen hundred and six earthquake city" , "US city renowned for its cable cars" , "Californian city" , "hilly city" , "US west coast port" .)