A dictator's cruel appearance (4)
I believe the answer is:
mien
'appearance' is the definition.
(I've seen this in another clue)
'a dictator's cruel' is the wordplay.
'a dictator's' indicates a 'sounds like' (homophone) clue (as somebody dictating would pronounce the word).
'cruel' becomes 'mean' (I've seen this in another clue).
'mean' sounds like 'MIEN'.
(Other definitions for mien that I've seen before include "A face - maybe mine" , "Person's appearance or manner" , "Personal bearing" , "attitude" , "(One's) manner, bearing" .)