Help! in calypso style (3)

I believe the answer is:

sos

'help' is the definition.
(emergency abbreviation SOS)

'in calypso style' is the wordplay.
'in' indicates the answer is hidden within the clue.
'SOS' can be found hidden inside 'calypso style'.

(Other definitions for sos that I've seen before include "Morse Code for help" , "Help code in 13 Across" , "Call for help" , "urgent appeal" , "Emergency message" .)

I've seen this clue in The Independent.

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