Players beginning to exhibit class (5)
I believe the answer is:
caste
'class' is the definition.
(caste is a kind of class)
'players beginning to exhibit' is the wordplay.
'players' becomes 'cast' (I've seen this before).
'beginning to' suggests taking the first letters.
The first letter of 'exhibit' is 'e'.
'cast'+'e'='CASTE'
(Other definitions for caste that I've seen before include "place in society" , "Persons with class" , "Hereditary social class in Hindu society" , "Social status" , "Group within society" .)