Get on with religious education in period (5)
I believe the answer is:
agree
'get on with' is the definition.
(thesaurus)
'religious education in period' is the wordplay.
'religious education' becomes 're'.
'in' means one lot of letters goes inside another.
'period' becomes 'age' (I've seen this before**).
're' put into 'age' is 'AGREE'.
(Other definitions for agree that I've seen before include "confess?" , "share the same view" , "Consent required" , "Be of one mind" , "Allow" .)