Foolishly angered English traitor (8)
I believe the answer is:
renegade
'traitor' is the definition.
(I've seen this in another clue)
'foolishly angered english' is the wordplay.
'foolishly' is an anagram indicator.
'english' becomes 'E' (abbreviation).
'angered' anagrammed gives 'renegad'.
'renegad'+'e'='RENEGADE'
(Other definitions for renegade that I've seen before include "disloyal type" , "Perfidious" , "not someone true to the cause" , "Dare Gene to become a rebel" , "Disloyal - defector" .)