Rude expression mugs rival off (9)

I believe the answer is:

vulgarism

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'rude expression' is the definition.
The definition and answer can be both human attributes as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

'mugs rival off' is the wordplay.
'off' is an anagram indicator.
'mugs'+'rival'='mugsrival'
'mugsrival' is an anagram of 'VULGARISM'.

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I've seen this clue in The Independent.

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