Is bass cornet playing in this? (5,7)

I believe the answer is:

brass section

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'this?' is the definition.
The definition suggests a singular noun which matches the answer.

'is bass cornet playing' is the wordplay.
'playing' indicates an anagram.
'is'+'bass'+'cornet'='isbasscornet'
'isbasscornet' is an anagram of 'BRASS SECTION'.

'in' acts as a link.

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I've seen this clue in The Times.

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