Rock star Billy useless when speaking (4)
I believe the answer is:
idol
'rock star billy' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'useless when speaking' is the wordplay.
'useless' becomes 'idle' (I've seen this in another clue).
'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 "Superstar; graven image" , "Object of excessive adoration" , "Pagan symbol" , "Worshipped figure (not painting); revered person" , "One much admired" .)