Crossword Genius

Outspoken music producer is transparent has-been? (7)

Ross

I believe the answer is:

spectre

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'outspoken music' is the definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for spectre that I've seen before include "Sceptre (anag.)" , "Ghost, phantom, apparition" , "after-image?" , "'Phantom, shade (7)'" , "Wraith" .)

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