Underground omen about musical device (9)

I believe the answer is:

metronome

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'musical device' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

'underground omen about' is the wordplay.
'underground' becomes 'metro' (synonyms).
'about' is an anagram indicator.
'omen' anagrammed gives 'nome'.
'metro'+'nome'='METRONOME'

Can you help me to learn more?

(Other definitions for metronome that I've seen before include "Device that sounds tempo for music practice" , "Ticker setting tempo of music" , "Device to indicate tempo" , "Musical timekeeper" , "Pendulum to indicate tempo of music" .)

I've seen this clue in The Daily Express.

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