A brief farewell (3)
I believe the answer is:
bye
This clue might be a double definition.
'a brief' is the first definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'farewell' is the second definition.
(I know that bye is a type of farewell)
Can you help me to learn more?
(Other definitions for bye that I've seen before include "Law of the local authority" , "Extra run in cricket" , "I'm off" , "Cricketing extra" , "Run scored in cricket from unhit ball" .)