Family title that's held by a knight, we hear (7)
I believe the answer is:
surname
'family title' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'held by a knight we hear' is the wordplay.
'held' becomes 'name' (I can't justify this - if you can you should believe this answer much more).
'by' means one lot of letters go next to another.
'a knight' becomes 'sir' (a knight has the title Sir).
'we hear' shows a homophone (sound like).
'sir' is a homophone of 'sur'.
'name' after 'sur' is 'SURNAME'.
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for surname that I've seen before include "Word by which a family is known" , "Family cognomen" , "Hereditary identifier" , "Family identifier" , "Last appellation" .)