What entertainer does for each class so nothing is forgotten (8)
I believe the answer is:
performs
'what entertainer does' is the definition.
'each class so nothing is forgotten' is the wordplay.
'each' becomes 'per'.
'class' becomes 'form' (form class is a kind of class).
'nothing' becomes 'o' (looks like zero - 0).
'is forgotten' is a deletion indicator.
'so' with 'o' taken away is 's'.
'per'+'form'+'s'='PERFORMS'
'for' acts as a link.
(Other definitions for performs that I've seen before include "Acts or executes" , "Carries out, accomplishes" , "Carries into effect or functions" , "Carries out, acts" , "Acts as in play" .)