Crossword Genius

Rising at first, but getting smaller overall (7)

Ross

I believe the answer is:

warning

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Here is my best explanation:

'rising at first' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe you can see a link between them that I don't see?

I can't explain the remainder of the clue.

Ross

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This clue was last seen in The Guardian

(Other definitions for warning that I've seen before include "Message informing of danger", "Cautionary advice", "caution", "Previous notice", "Caution - threat", "Advance notice" and "Tip-off".)

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