One shrugs of crudeness (9)

I believe the answer is:

roughness

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'crudeness' is the definition.
(synonyms)

'one shrugs' is the wordplay.
'one shrugs' anagrams to 'ROUGHNESS'.
But, I'm not clear how the anagram is indicated.

'of' is the link.

Can you help me to learn more?

(Another definition for roughness that I've seen is " Hoarse quality".)

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

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