Unoriginal work theatre has hosted in part (6)
I believe the answer is:
rehash
'unoriginal work' is the definition.
(rehash of earlier work)
'theatre has hosted in part' is the wordplay.
'in part' indicates a hidden word.
'REHASH' is hidden in the letters of 'theatre has hosted'.
(Other definitions for rehash that I've seen before include "That's nothing really new" , "Reuse (old ideas) with little improvement" , "Serve up old ideas" , "Put old material into new form without much change" , "Old material, slightly reworked and used again" .)