City's unusually long leases (3,7)
I believe the answer is:
los angeles
'city's' is the definition.
(Los Angeles is an example)
'unusually long leases' is the wordplay.
'unusually' indicates anagramming the letters.
'long'+'leases'='longleases'
'longleases' with letters rearranged gives 'LOS ANGELES'.
(Other definitions for los angeles that I've seen before include "city on Pacific" , "Hollywood's city" , "Second most populous city in the US" , "Hollywood city" , "centre of population" .)