Make one’s mark in plea over a major departure from scripture (6)
I believe the answer is:
exodus
'departure from scripture' is the definition.
'exodus' can be an answer for 'departure' (I've seen this before). I am not sure about the 'from scripture' bit.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for exodus that I've seen before include "OT book - flight" , "Film of book" , "a mass departure as in Bible Book" , "Old Testament Book 2" , "Journey of escape" .)