A long intro from Hendrix? (5)
I believe the answer is:
aitch
'intro from hendrix?' 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?
'a long' is the wordplay.
'long' becomes 'itch' (to long or itch for something is to desire it).
'a'+'itch'='AITCH'
(Other definitions for aitch that I've seen before include "8th letter of the alphabet" , "bone" , "first bit of hymn?" , "It's dropped by Cockneys" , "what some drop?" .)