Not showing dukes to be charitable (4-6)

I believe the answer is:

open-handed

I believe this is a double definition.

'not showing dukes' is the first definition.
(duke can mean one's fist)

'charitable' is the second definition.
(thesaurus)

'to be' acts as a link.

(Other definitions for open-handed that I've seen before include "Generous" , "Big-hearted?" .)

I've seen this clue in The Times.

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