The Italian title used by Mussolini (4)

I believe the answer is:

duce

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'mussolini' is the definition.
(I've seen this in another clue)

I can't explain the rest of the clue.

(Other definitions for duce that I've seen before include "Italian leader" , "Mussolini" , "Mussolini's title" .)

I've seen this clue in the Evening Standard.

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