The hard facts one may get back to (6)
I believe the answer is:
basics
'the hard facts' is the definition.
The answer and definition can be both related to communication as well as being plural nouns.
Perhaps you can see a link between them that I don't see?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for basics that I've seen before include "Fundamentals, starting-points" , "Rudiments" , "Essential principles" .)