With Carlo he produces tune (7)
I believe the answer is:
chorale
'tune' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'with carlo he produces' is the wordplay.
'with' says to put letters next to each other.
'produces' is an anagram indicator.
'carlo' next to 'he' is 'carlohe'.
'carlohe' with letters rearranged gives 'CHORALE'.
Can you help me to learn more?
(Other definitions for chorale that I've seen before include "Stately hymn tune" , "Psalm or hymn tune" , "Composition" , "hymn setting" , "Lutheran hymn-tune" .)