Ancient instrument, part of brass, is trumpet (7)

I believe the answer is:

sistrum

'ancient instrument' is the definition.
(I've seen this before)

'part of brass is trumpet' is the wordplay.
'part of' says the answer is hidden in the clue.
'SISTRUM' is hidden within 'brass is trumpet'.

(Another definition for sistrum that I've seen is " Ancient instrument".)

I've seen this clue in The Times.

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