Dark colour that might be deadly (10)

I believe the answer is:

nightshade

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'dark colour that might be deadly' is the definition.
The definition suggests a singular noun which matches the answer.

'dark colour' is the wordplay.
'dark' becomes 'night' (it's dark at nighttime).
'colour' becomes 'shade' (shade is a kind of colour).
'night'+'shade'='NIGHTSHADE'

Can you help me to learn more?

(Other definitions for nightshade that I've seen before include "Plant, maybe deadly" , "protection from the moon's brightness?" , "See 3" , "Poisonous plant" , "Belladonna" .)

I've seen this clue in The Globe and Mail.

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