Minor performers no longer rubbish? Not entirely (6)
I believe the answer is:
extras
'minor performers' is the definition.
(extras are minor actors)
'no longer rubbish? not entirely' is the wordplay.
'no longer' becomes 'ex' (prefix meaning former or onetime).
'rubbish?' becomes 'trash' ('trash' can be a synonym of 'rubbish').
'not entirely' means to remove the last letter.
'trash' with its final letter taken away is 'tras'.
'ex'+'tras'='EXTRAS'
(Other definitions for extras that I've seen before include "Runs not scored from the bat" , "minor players?" , "Bit actors in film" , "Wides, no-balls, etc." , "Bit players, actors without dialogue" .)