Country’s king essentially favours disorder (7)
I believe the answer is:
romania
'country's' is the definition.
(Romania is an example)
'king essentially favours disorder' is the wordplay.
'king' becomes 'R' (abbreviation for rex, king in Latin).
'essentially' says to take the centre.
'disorder' becomes 'mania' (mania is a kind of disorder).
The central letter of 'favours' is 'o'.
'r'+'o'+'mania'='ROMANIA'
(Other definitions for romania that I've seen before include "European republic" , "EU country" , "Country in SE Europe" , "Country of eastern Europe" , "Eastern European country" .)