Sioux City's state (4)
I believe the answer is:
iowa
'sioux city's state' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for iowa that I've seen before include "US swing electoral state" , "State of USA" , "part of US" , "part of United States" , "American state, capital Des Moines" .)