Words repeated in four-letter torrent undermining referee (7)
I believe the answer is:
refrain
'words repeated in' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe there's an association between them I don't understand?
'four-letter torrent undermining referee' is the wordplay.
'four letter torrent' becomes 'rain' (I can't justify this - if you can you should give a lot more credence to this answer).
'undermining' is a charade indicator (letters next to each other).
'referee' becomes 'ref' ('ref' can be a synonym of 'referee').
'rain' after 'ref' is 'REFRAIN'.
Can you help me to learn more?
(Other definitions for refrain that I've seen before include "tune" , "recurring phrase" , "The repeated lines at the end of verses" , "Hold back" , "Chorus of a song" .)