Wealthier doctor, on losing 1/3rd becomes a tyrant (6)

I believe the answer is:

hitler

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But I can't explain it at all! Could you help me understand?

(Other definitions for hitler that I've seen before include "German F?hrer" , "German dictator" , "Nazi dictator" , "Adolf, who made people heil" , "German Chancellor and Fuhrer, nineteen thirty three to nineteen forty five" .)

I've seen this clue in The Hindu.

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