Top jazz songstress? A star (7)

I believe the answer is:

capella

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'star' is the definition.
(Capella is an example)

'top jazz songstress? a' is the wordplay.
'top' becomes 'cap' (both can mean to beat or outdo).
'jazz songstress?' becomes 'ell' (I am not sure about this - if you are sure you should believe this answer much more).
'cap'+'ell'+'a'='CAPELLA'

Can you help me to learn more?

(Other definitions for capella that I've seen before include "Star in Auriga; Laplace (anag.)" , "One of the brighest stars" , "First-magnitude star" .)

I've seen this clue in The Times.

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