Turner sketched a general, partly from the rear (8)
I believe the answer is:
renegade
'turner' is the definition.
(turner can mean a renegade)
'sketched a general partly from the rear' is the wordplay.
'partly' says the answer is hidden in the clue (part of the clue is used).
'from the rear' says the letters should be written backwards.
'edagener' is hidden in the letters of 'sketched a general'.
'edagener' backwards is 'RENEGADE'.
(Other definitions for renegade that I've seen before include "Turncoat, rebel" , "Treacherous person" , "Traitor" , "disloyal type" , "Perfidious" .)