I believe the answer is:
'obote's deposer' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for amin that I've seen before include "'Idi ..., former Ugandan ruler (4)'" , "Dictator Idi --" , "Idi . . . . Once ruled Uganda tyrannically" , "Ugandan dictator" , "Brutal dictator" .)