Show main tempo needs changing (9)
I believe the answer is:
pantomime
'show' is the definition.
(I've seen this before)
'main tempo needs changing' is the wordplay.
'needs changing' is an anagram indicator (I've seen this in other clues).
'main'+'tempo'='maintempo'
'maintempo' anagrammed gives 'PANTOMIME'.
(Other definitions for pantomime that I've seen before include "Traditional Christmas stage show with Dame" , "farce" , "Play performed at Christmas" , "Festive stage show" , "eg 'Mother Goose'" .)