Girl's staidness cracked: maybe a flare-up (8,6)

I believe the answer is:

distress signal

'maybe a flare-up' is the definition.
(a flare may be set off as a distress signal)

'girl's staidness cracked' is the wordplay.
'cracked' indicates anagramming the letters.
'girls'+'staidness'='girlsstaidness'
'girlsstaidness' anagrammed gives 'DISTRESS SIGNAL'.

(Another definition for distress signal that I've seen is " indication that urgent help is needed".)

I've seen this clue in The Guardian.

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