Not a whisper to the audience! (5)
I believe the answer is:
Here is my best explanation:
'the audience' 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?
'not a whisper' is the wordplay.
I cannot really see how this works, but
'a' is found in the answer.
The remaining letters 'side' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'to' acts as a link.
(Other definitions for aside that I've seen before include "(Turn) off main path", "Remark not for hearing", "Ideas (anag)", "In reserve -- confidential remark", "Away from main action", "private", "I.e. sad (anag.)", "Out of the way", "In reserve; actor's remark to audience" and "An actor's remark to the audience".)