It's traditionally said to do the trick (11)
I believe the answer is:
abracadabra
'do the trick' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for abracadabra that I've seen before include "Magic word used by conjurors" , "for a spell it is declared" , "Word used by conjuror" , "it's said, for a spell" , "Word said to trick" .)