Northwest US state (5)
I believe the answer is:
idaho
'northwest us state' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for idaho that I've seen before include "Pertaining to the Bard" , "part of US near Washington" , "State of northwest US" , "The Gem State, known for its potatoes" , "North-western US state" .)