Nina's pigs scattered while she was doing something else (2,7)

I believe the answer is:

in passing

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'while she was doing something else' is the definition.
I can't judge whether this definition defines the answer.

'nina's pigs scattered' is the wordplay.
'scattered' indicates an anagram.
'ninas'+'pigs'='ninaspigs'
'ninaspigs' anagrammed gives 'IN PASSING'.

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(Other definitions for in passing that I've seen before include "Where footballer may show skill" , "by the way" , "casually" .)

I've seen this clue in The Independent.

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