Cast to repeat show (8)
I believe the answer is:
operetta
'show' is the definition.
(I've seen this before)
'cast to repeat' is the wordplay.
'cast' indicates anagramming the letters (letters are dispersed or cast around).
'to'+'repeat'='torepeat'
'torepeat' with letters rearranged gives 'OPERETTA'.
(Other definitions for operetta that I've seen before include "The Merry Widow, for example" , "some music theatre" , "Short amusing opera" , "Eight dn, for instance" , "Musical entertainment" .)