Bill singing well? (7)
I believe the answer is:
invoice
This could be a double definition.
'bill' is the first definition.
(invoicing is a kind of billing)
'singing well?' is the second definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for invoice that I've seen before include "List of goods supplied and request for payment" , "Demand for payment" , "Statement of sum due" , "Pollen holder" , "Statement of money owed" .)