Duke's number 501, absorbed by what cow says to dog (4,6)

I believe the answer is:

mood indigo

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'duke's number' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'501 absorbed by what cow says to dog' is the wordplay.
'501' becomes 'di'.
'absorbed by' indicates putting letters inside.
'what cow says' becomes 'moo' (noise made by a cow).
'to dog' becomes 'dingo' (I've seen this before).
'moo'+'dingo'='moodingo'
'di' inserted into 'moodingo' is 'MOOD INDIGO'.

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(Another definition for mood indigo that I've seen is " Duke Ellington song".)

I've seen this clue in The Guardian.

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