Nevada's "Biggest Little City in the World" (4)
I believe the answer is:
reno
'nevada's biggest little city in the world' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for reno that I've seen before include "American city" , "gambling centre" , "Nevadan city" , "Nevada city of Nero" , "Nevada gambling resort" .)