My best guess as to WHAT is:
??V?ENT of FORMER PRESBYTRY
but that does not make much sense
If the first word is ??V??NT which looks very possible the Crossword Solver is suggesting DEVIANT as only possible answer. On that basis, I suspect it is not ??V??NT.
As to WHY, it looks to neat and deliberate to be vandalism. Maybe it was incorrect. Maybe just misspelt.
It remains a riddle.