Crossword Genius

Curved branch splits from the bottom, the noise waking you? (6,3)

Ross

I believe the answer is:

spiral arm

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'splits from the bottom the noise waking you?' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'curved branch' is the wordplay.
'curved' becomes 'spiral' (I am not sure about this - if you are sure you should believe this answer much more).
'branch' becomes 'arm' (synonyms).
'spiral'+'arm'='SPIRAL ARM'

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I've seen this clue in The Times.
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