Crossword Genius

Low-pitched noise from this replacement dog (9)

Ross

I believe the answer is:

subwoofer

'low-pitched noise from this' is the definition.
(type of speaker)

'replacement dog' is the wordplay.
'replacement' becomes 'sub' (I've seen this before).
'dog' becomes 'woofer'.
'sub'+'woofer'='SUBWOOFER'

I've seen this clue in The Guardian.
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