A piece of yarn (7)
I believe the answer is:
episode
'yarn' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe there's an association between them I don't understand?
'a piece' is the wordplay.
I cannot quite see how this works, but
'piece' could be 'sod' (I have seen 'Piece of turf' mean 'sod' so perhaps 'piece' could also mean 'sod') and 'sod' is found in the answer.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for episode that I've seen before include "Distinctive happening" , "Set of incidents" , "One of a related series of events" , "Chapter or event" , "Instalment of a TV series" .)