Pop star Billy useless when speaking (4)

I believe the answer is:

idol

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'pop star billy' is the definition.
'idol' can be an answer for 'billy' (I've seen this before). I'm unsure of the 'pop star' bit.

'useless when speaking' is the wordplay.
'useless' becomes 'idle' (I've seen this before).
'when speaking' shows a homophone (sound like).
'idle' is a homophone of 'IDOL'.

Can you help me to learn more?

(Other definitions for idol that I've seen before include "Pop - - (TV)" , "A graven image or object of adoration" , "'There's a one-eyed yellow -' (Hayes)" , "Darling" , "Heathen god" .)

I've seen this clue in The Sun.

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