Crossword Genius

A cloud of smoke is said to cause dismay (5)

Ross

I believe the answer is:

appal

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'dismay' is the definition.
(I know that dismay can be written as appal)

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for appal that I've seen before include "Outrage" , "expressed dismay" , "Cause to be unpleasantly surprised" , "Greatly horrify" , "Scandalise" .)

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