Show at one has to be put back (5)
I believe the answer is:
evita
'show' is the definition.
(musical by Andrew Lloyd Webber)
'at one has to be put back' is the wordplay.
'one has' becomes 'I've' ('one has' can formally or humorously mean 'I have').
'to be put back' says the letters should be written backwards.
'at'+'ive'='ative'
'ative' reversed gives 'EVITA'.
(Other definitions for evita that I've seen before include "Andrew Lloyd Webber musical set in Argentina" , "Eva Peron" , "Musical based on Argentine leader" , "Juan Peron's wife" , "Peron musical" .)