Second half's disastrous (5)

I believe the answer is:

flash

'second' is the definition.
(thesaurus)

'half's disastrous' is the wordplay.
'disastrous' indicates an anagram.
'halfs' with letters rearranged gives 'FLASH'.

(Other definitions for flash that I've seen before include "short space of time" , "Brief burst of light" , "Briefly shine, short flood" , "Twinkling" , "Instant" .)

I've seen this clue in The Times.

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