Some words, on leaving model, hit hard (9)
I believe the answer is:
paragraph
'some words' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'leaving model hit hard' is the wordplay.
I cannot really see how this works, but
'hit' could be 'par' (parring is a kind of hitting) and 'par' is present in the answer.
'hard' could be 'h' (abbreviation used in pencil classifications) and 'h' is present in the answer.
This explanation may well be incorrect...
'on' acts as a link.
Can you help me to learn more?
(Other definitions for paragraph that I've seen before include "Section of written work" , "section of text" , "A group of connected sentences" , "Passage" , "short item" .)