Crossword Genius

A groundless scare - from a faulty clock? (5,5)

Ross

I believe the answer is:

false alarm

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'a groundless scare' is the definition.
The definition suggests a singular noun which matches the answer.

'a faulty clock?' is the wordplay.
'a faulty' becomes 'false' (I can't justify this - if you can you should give a lot more credence to this answer).
'clock?' becomes 'alarm' (alarm is a kind of clock).
'false'+'alarm'='FALSE ALARM'

'from' acts as a link.

Can you help me to learn more?

(Other definitions for false alarm that I've seen before include "unfounded scare?" , "Warning proving unnecessary" , "Panic over" .)

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