Nebraska's biggest city (5)
I believe the answer is:
omaha
'nebraska's biggest city' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for omaha that I've seen before include "This was old Indian territory" , "US 1944 D-Day landing beach" , "American town" , "Nebraska's largest city" , "- - Beach (WWII)" .)