Yes, along with other advanced fee frauds, it's an offence. Typically clipping is done in connection with things where the victim is unlikely to go to the police ('I was kerb-crawling / buying drugs, and...')
I think we can take it as read that it is not a good thing to do - even if you ignore the legality and the morality, some victims will come looking for violent revenge - but a look at 'would not recommend' reviews will indeed find some samples of people doing it one way or another.