Take a breath on ridiculous gradient going on the stage without any preparation (5-7)

I believe the answer is:

sight-reading

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'going on the stage without any preparation' is the definition.
I can't tell whether this definition defines the answer.

'take a breath on ridiculous gradient' is the wordplay.
'take a breath' becomes 'sigh' (sighing is a kind of taking a breath).
'on' says to put letters next to each other.
'ridiculous' indicates an anagram.
'gradient' anagrammed gives 'treading'.
'sigh'+'treading'='SIGHT-READING'

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I've seen this clue in The Irish Times.

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