Unrehearsed, awful panto's no use (11)

I believe the answer is:

spontaneous

'unrehearsed' is the definition.
(thesaurus)

'awful panto's no use' is the wordplay.
'awful' indicates an anagram.
'pantos'+'no'+'use'='pantosnouse'
'pantosnouse' anagrammed gives 'SPONTANEOUS'.

(Other definitions for spontaneous that I've seen before include "Cause of Mr Krook's death" , "Unprompted" , "Impulsive, unpremeditated" , "Impromptu" .)

I've seen this clue in The Telegraph.

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