Not going on to give instructions (5)
I believe the answer is:
brief
'instructions' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe they are linked in a way I don't understand?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for brief that I've seen before include "Ephemeral" , "Brusque - lawyer (slang)" , "Short or concise" , "scanty" , "Short in duration" .)