The state of a man not getting upset (7)
I believe the answer is:
montana
'the state' is the definition.
(state of the US)
'a man not getting upset' is the wordplay.
'getting upset' indicates anagramming the letters.
'a'+'man'+'not'='amannot'
'amannot' anagrammed gives 'MONTANA'.
'of' acts as a link.
(Other definitions for montana that I've seen before include "North-western state bordering Canada" , "American state, capital Helena" , "State N. of Wyoming" , "North-western US state" , "State of NW USA" .)