High-ranking Mafioso has enemy leader polished off (4)

I believe the answer is:
done
Here is my best explanation:
'polished off' is the definition.
(when one is 'polished off' they are done)
'high-ranking mafioso has enemy leader' is the subsidiary indication.
'high-ranking mafioso' becomes 'don' (a don is a high-ranking mafioso).
'has' is a charade indicator (letters next to each other).
'leader' indicates taking the first letters.
The initial letter of 'enemy' is 'e'.
'don'+'e'='done'
(Other definitions for done that I've seen before include "Swindled", "Cooked; carried out", "Achieved", "Finished or ended", "Thoroughly cooked; accomplished", "See 23", "Finished like node", "Artist's workroom", "Performed" and "(Of food) well cooked".)

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