Long leases unusual in city (3,7)
I believe the answer is:
los angeles
'city' is the definition.
(Los Angeles is an example)
'long leases unusual' is the wordplay.
'unusual' indicates anagramming the letters.
'long'+'leases'='longleases'
'longleases' with letters rearranged gives 'LOS ANGELES'.
'in' is the link.
(Other definitions for los angeles that I've seen before include "Californian city" , "LA, California" , "Big city" , "city abroad" , "Hollywood's city" .)