Executed one in dividends? (3)

I believe the answer is:

did

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'executed' is the definition.
(doing is a kind of executing)

'one in dividends?' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in' means one lot of letters goes inside another.
'dividends?' becomes 'dd' (I can't explain this - if you can you should believe this answer much more).
'i' inserted inside 'dd' is 'DID'.

Can you help me to learn more?

(Other definitions for did that I've seen before include "Swindled" , "Acted" , "Accomplished" , "Performed an action" , "Carried out, performed" .)

I've seen this clue in the Sydney Morning Herald.

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