Dictionary entry's origin in light Austen novel (5)
I believe the answer is:
lemma
'dictionary entry's' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'origin in light austen novel' is the wordplay.
'origin in' indicates taking the first letters.
'austen novel' becomes 'Emma' (novel by Jane Austen).
The first letter of 'light' is 'l'.
'l'+'emma'='LEMMA'
Can you help me to learn more?
(Other definitions for lemma that I've seen before include "heading" , "Intermediate proof" , "Proposition" , "Subsidiary theorem" , "Subject's division" .)