### Clue: Deal twinned with medium US city (5)
### Answer: SALEM 
 ### Explanation: Definition: US city
 SALE(a deal between a buyer and a seller of an item) **plus**(with) M(abbrev. for "medium", as in clothing sizes).
Defn: … in Massachusetts.
Whereas the town of Deal in Kent is actually twinned with Saint-Omer, France and Vlisssingen, the Netherlands.