Grandee disturbed about English traitor (8)
I believe the answer is:
renegade
'traitor' is the definition.
(thesaurus)
'grandee disturbed about english' is the wordplay.
'disturbed' is an anagram indicator.
'about' means one lot of letters goes inside another.
'english' becomes 'e' (abbreviation).
'grandee' anagrammed gives 'rnegade'.
'rnegade' placed around 'e' is 'RENEGADE'.
(Other definitions for renegade that I've seen before include "Person who deserts from cause or faith" , "Deserter, turncoat" , "Rebel deserter" , "Traitor" , "One who deserts a cause or group" .)