Change religious education class (6)
I believe the answer is:
reform
'change' is the definition.
(reform is a kind of change)
'religious education class' is the wordplay.
'religious education' becomes 're'.
'class' becomes 'form' (form class is a kind of class**).
're'+'form'='REFORM'
(Other definitions for reform that I've seen before include "Removal of abuses" , "Mend one's ways" , "Change one's ways (for the better?)" , "Show improvement" , "Correct(ion of) abuses" .)