Idiot and nonchalant revolutionary in old kingdom (7)
I believe the answer is:
assyria
'old kingdom' is the definition.
(ancient Middle Eastern kingdom)
'idiot and nonchalant revolutionary' is the wordplay.
'idiot' becomes 'ass' (I've seen this in other clues).
'and' says to put letters next to each other.
'nonchalant' becomes 'airy' (airy can mean casual or unconcerned).
'revolutionary' says the letters should be written backwards.
'airy' backwards is 'yria'.
'ass'+'yria'='ASSYRIA'
'in' acts as a link.
(Other definitions for assyria that I've seen before include "Ancient Middle East kingdom - Ira says (anag)" , "Ancient Semitic kingdom" , "old empire" , "Ancient empire of Iraq" , "expansionist kingdom" .)