Certain cast member (7)
(Other definitions for actress that I've seen before include "Female in theatre" , "Casters (anag.)" , "One on stage" , "Female thespian" , "One playing" .)
(Other definitions for extra that I've seen before include "No great contribution to film" , "person in shot?" , "small-time actor" , "No-ball or wide, perhaps?" , "23 player?" .)