Do that which makes quiet impossible? (5)
I believe the answer is:
shout
'do that which' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'quiet impossible?' is the wordplay.
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'impossible?' becomes 'out' (out can mean no longer possible).
'sh'+'out'='SHOUT'
'makes' is the link.
Can you help me to learn more?
(Other definitions for shout that I've seen before include "Yell" , "Bawl" , "Raise one's voice" , "Loud call" , "Call loudly" .)