Crossword Genius

Perspicacity unwelcome in performing musicians? (9)

Ross

I believe the answer is:

sharpness

'perspicacity' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Perhaps there's a link between them I don't understand?

I don't understand how the rest of the clue works.

(Other definitions for sharpness that I've seen before include "Being quick to perceive" , "Acuity; Severn port" , "faulty intonation" , "Clarity" .)

I've seen this clue in The Times.
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