Literal holy sin? (8,5)

I believe the answer is:
clerical error
'literal' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'holy sin?' is the wordplay.
'holy' becomes 'clerical' (I can't explain this - if you can you should give a lot more credence to this answer).
'sin?' becomes 'error' (I've seen this in another clue).
'clerical'+'error'='CLERICAL ERROR'
Can you help me to learn more?
(Other definitions for clerical error that I've seen before include "Mistake in paperwork" , "Mistake in the office?" .)
