Respect witness (6)
I believe the answer is:
regard
This clue might be a double definition.
'respect' is the first definition.
(synonyms)
'witness' is the second definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
Can you help me to learn more?
(Other definitions for regard that I've seen before include "Consideration" , "Concern" , "Watch" , "Look closely at" , "Consider, view" .)