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 really understand how this works, but
an anagram of 'evil' is 'veil' which is present in the answer.
'one' could be 'un' (northern English dialect form of 'one') and 'un' is present in the answer.
'german' could be 'g' (abbreviation) and 'g' is located in the answer.
The remaining letters 'in' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...

Can you help me to learn more?