Country governed by leader in Borneo: that is revolutionary (6)
I believe the answer is:
brunei
'country' is the definition.
(I know that Brunei is a country)
'governed by leader in borneo that is revolutionary' is the wordplay.
'governed' becomes 'run'.
'by' is a charade indicator (letters next to each other).
'leader in' indicates taking the first letters.
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'revolutionary' says the letters should be written in reverse.
The initial letter of 'borneo' is 'b'.
'ie' written backwards gives 'ei'.
'run' put after 'b' is 'brun'.
'brun'+'ei'='BRUNEI'
(Other definitions for brunei that I've seen before include "Commonwealth country" , "Sultanate of southeast Asia" , "Sultanate in northwest Borneo" , "Muslim state" , "State on Borneo" .)