Crossword Genius

Say backing away from offence is a shadowy area (5)

Ross

I believe the answer is:

umbra

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'say' is the definition.
The answer and definition can be both states of affairs as well as being singular nouns.
Maybe you can see an association between them that I can't see?

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

Can you help me to learn more?

(Other definitions for umbra that I've seen before include "Shade, or ghost" , "Dark region" , "Rumba (anag.)" , "Dark shadow cast by earth in eclipse" , "Black spot" .)

I've seen this clue in The Guardian.
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