Dictator's top dog (4)
I believe the answer is:
peke
'dog' is the definition.
(short for Pekingese)
'dictator's top' is the wordplay.
'dictator's' shows a homophone (sound like) (as somebody dictating would pronounce the word).
'top' becomes 'peak' (synonyms).
'peak' is a homophone of 'PEKE'.
(Other definitions for peke that I've seen before include "Snub-nosed lap-dog (colloq.)" , "5 [MANS BEST FRIEND]" , "Little dog" , "Small canine" , "Sort of lapdog" .)