Presumably uncommunicative authority (3-2)

I believe the answer is:

say-so

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'authority' is the definition.
(I know that authority can be written as say-so)

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for say-so that I've seen before include "Authorisation" , "Final authority" , "Authority - rumour" , "Authority to make or allow something to happen" , "Arbitrary assertion" .)

I've seen this clue in The Independent.

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