Most panicky opener vies to stretch (8)

I believe the answer is:

nerviest

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'most panicky' is the definition.
Both the answer and definition are superlative adjectives. Maybe you can see an association between them that I can't see?

'opener vies to stretch' is the wordplay.
'NERVIEST' is hidden in amongst the letters.
But, I am not sure how this is indicated.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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