Boy creeping up behind vehicle? He is a desecrater (6)
I believe the answer is:
vandal
But I can't explain it at all! Could you help me understand?
(Other definitions for vandal that I've seen before include "Wanton wrecker" , "One of those who sacked Rome in 455" , "Defacer or wrecker" , "One who damages things maliciously" , "Destroyer or defacer of property" .)