The Scarlet Letter , with long introduction from Hawthorne (5)
I believe the answer is:
aitch
'introduction from hawthorne' 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?
'the scarlet letter with long' is the wordplay.
'the scarlet letter' becomes 'a' (I am not sure about the 'scarlet' bit.).
'with' means one lot of letters go next to another.
'long' becomes 'itch' (to long or itch for something is to desire it).
'a'+'itch'='AITCH'
Can you help me to learn more?
(Other definitions for aitch that I've seen before include "The letter h in full" , "first bit of hymn?" , "that I will immediately succeed" , "the start of hives?" , "Letter sound that's often dropped?" .)