We understand it to be communicative (7)
I believe the answer is:
english
'communicative' is the definition.
Both the answer and definition are adjectives. Maybe there's a link between them I don't understand?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for english that I've seen before include "This nationality found in shingle" , "speech" , "Widely-spoken language" , "Language of the shingle?" , "side" .)