Bill — and what he hopes to be when singing? (7)
I believe the answer is:
invoice
'bill' is the definition.
(I know that bill can be written as invoice)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for invoice that I've seen before include "Pollen holder" , "Document detailing costs - ready to sing (7;2,5)" , "Account; bill" , "Give account" , "List of goods supplied and request for payment" .)