Brief musical opening (5)
I believe the answer is:
intro
This might be a double definition.
'brief' is the first 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?
'musical opening' is the second definition.
(short for introduction)
Can you help me to learn more?
(Other definitions for intro that I've seen before include "Lead-in" , "First part of a news story (abbr)" , "Preliminary part" , "Lead" , "Opening passage (of music) (colloq.)" .)