Part of church service proceeding slowly (7)
I believe the answer is:
gradual
'part' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for gradual that I've seen before include "Little by little, not too fast" , "Progressive" , "Progressing slowly" , "Gentle; slow" , "mass response" .)