Scoffing a lot of jam's a crass backsliding (7)
I believe the answer is:
sarcasm
'scoffing' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'a lot of jam's a crass backsliding' is the wordplay.
'a lot of' indicates the answer is hidden within the clue (I've seen 'a lot' mean this (a lot of the letters from the clue)).
'backsliding' says the letters should be written backwards.
'msacras' is hidden in the letters of 'jams a crass'.
'msacras' written backwards gives 'SARCASM'.
Can you help me to learn more?
(Other definitions for sarcasm that I've seen before include "Mordancy" , "Ironical remark or taunt" , "Gibe" , "Language expressing scorn or contempt" , "Show of ironic contempt" .)