Theatre work ... um ... non-starter (2-5)
I believe the answer is:
no-hoper
'non-starter' is the definition.
'theatre work um' is the wordplay.
'theatre' becomes 'noh' (Japanese drama).
'work' becomes 'op' (abbreviation for opus).
'um' becomes 'er' (both said to fill in hesitation when speaking).
'noh'+'op'+'er'='NO-HOPER'
(Other definitions for no-hoper that I've seen before include "One not expected to succeed" , "Person expected to fail" , "One with little prospect of success" , "Lost cause" , "One with no prospects" .)