Terribly evil nun excited about one German's revelation (9)

'revelation' is the definition.
(thesaurus)

'terribly evil nun excited about one german's' is the wordplay.
I cannot quite see how this works, but
an anagram of 'evil' is 'veil' which is located in the answer.
'one' could be 'un' (northern English dialect form of 'one') and 'un' is located in the answer.
'german' could be 'g' (abbreviation) and 'g' is found in the answer.
The remaining letters 'in' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?