Chinese dynasty's seventh child (4)
I believe the answer is:
song
'chinese dynasty's seventh' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe there's a link between them I don't understand?
'child' is the wordplay.
I cannot really see how this works, but
'child' could be 'son' (male child) and 'son' is found in the answer.
A single letter 'g' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for song that I've seen before include "Ballad, aria" , "Lied" , "Carol, for instance" , "Carol, for example" , "Unnecessary fuss" .)