US state a right state! (8)
I believe the answer is:
arkansas
'us state' is the definition.
(Arkansas is a US state)
'a right state' is the wordplay.
'a right' becomes 'ar' (I've seen this in other clues).
'state' becomes 'kansas' (Kansas is an example).
'ar'+'kansas'='ARKANSAS'
(Other definitions for arkansas that I've seen before include "State of S. central US" , "Little Rock's state" , "used to be a Land of Opportunity" , "River joining Mississippi" , "American river and state" .)