Crossword Genius

Salmon oil, a regular early pro­tection for young vertebrates (5)

Ross

I believe the answer is:

amnia

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'early protection for young vertebrates' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'salmon oil a regular' is the wordplay.
'regular' indicates alternate letters.
'salmon'+'oil'+'a'='salmonoila'
The alternate letters of 'salmonoila' are 'AMNIA'.

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(Another definition for amnia that I've seen is " First bodyguards".)

I've seen this clue in The Guardian.
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