Instructions Spooner's group catch (8)
I believe the answer is:
handbook
'instructions' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe there's a link between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for handbook that I've seen before include "Guide" , "companion" , "Manual, reference" .)