Legal proof that you’re the champion? (5,4)
I believe the answer is:
title deed
'legal proof' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe there's an association between them I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for title deed that I've seen before include "Document proving ownership" , "Having proof of ownership" , "Document giving legal right of ownership" , "proper document" , "Deleted it (anag.)" .)