Pass on joke you hear in summarised version (6)
I believe the answer is:
digest
'pass' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for digest that I've seen before include "Assimilate (mentally)" , "Assimilate - summary" , "Take in (information or food)" , "publication" , "Think over, absorb into the mind" .)