A Greek style (5)
I believe the answer is:
alpha
This clue could be a double definition.
'a' is the first definition.
(the Greek letter A)
'greek style' is the second definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps there's a link between them I don't understand?
Can you help me to learn more?
(Other definitions for alpha that I've seen before include "Foremost" , "Most prominent star" , "First-rate" , "First in sequence" , "First, best quality" .)