Elgar isn't bad — do they tinkle in his music? (9)

I believe the answer is:

triangles

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'do they tinkle in his music?' is the definition.
The definition suggests a singular noun but the answer is a plural noun.

'elgar isn't bad' is the wordplay.
'bad' is an anagram indicator.
'elgar'+'isnt'='elgarisnt'
'elgarisnt' with letters rearranged gives 'TRIANGLES'.

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(Other definitions for triangles that I've seen before include "Geometrical figures" , "Three-sided shapes" , "Three-sided figures" , "Musical instruments" , "Three-sided polygons" .)

I've seen this clue in The Times.

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