Small crest isn't about severity (10)

I believe the answer is:

strictness

'severity' is the definition.
(thesaurus)

'small crest isn't about' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'about' is an anagram indicator.
'crest'+'isnt'='crestisnt'
'crestisnt' is an anagram of 'trictness'.
's'+'trictness'='STRICTNESS'

I've seen this clue in The Daily Express.

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