Dismay; a warning device (5)

I believe the answer is:

alarm

This clue is a double definition.

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

'a warning device' is the second definition.
(synonyms)

(Other definitions for alarm that I've seen before include "Scare with warning device" , "Burglar deterrent" , "Feeling of fear" , "Flap" , "Put the wind up" .)

I've seen this clue in the Sydney Morning Herald.

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