An explosive utterance (5)
I believe the answer is:
blast
'an explosive utterance' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe they are linked in a way I don't understand?
This is all the clue.
Can you help me to learn more?
(Other definitions for blast that I've seen before include "Mild expletive - sharp explosion" , "Sudden strong gust of wind" , "Effect of explosion" , "Great time: explosion" , "Blow up with explosives" .)