Class actors, English (5)
I believe the answer is:
caste
'class' is the definition.
(type of social class)
'actors english' is the wordplay.
'actors' becomes 'cast' (group of actors).
'english' becomes 'E' (abbreviation as in OED).
'cast'+'e'='CASTE'
(Other definitions for caste that I've seen before include "Social class or rank" , "Hindu determinant of status" , "place in society" , "Hereditary class (in India)" , "Social system" .)