About duke being scumbag (3)

I believe the answer is:

cad

I'm a little stuck... Click here to teach me more about this clue!

'scumbag' is the definition.
I can't tell whether this definition defines the answer.

'about duke' is the wordplay.
'about' becomes 'ca' (abbreviation for 'circa').
'duke' becomes 'd'.
'ca'+'d'='CAD'

'being' acts as a link.

Can you help me to learn more?

(Other definitions for cad that I've seen before include "Rotter, bounder" , "A rotten chap, no integrity" , "A rotter, by Jove" , "Wretch" , "designing software" .)

I've seen this clue in The Mirror.

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