Ponzi scheme, for example (4)
I believe the answer is:
scam
'ponzi scheme for example' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for scam that I've seen before include "Swindle, fraud (colloq.)" , "An informal swindle" , "fiddle" , "Racket" , "Swindle (sl.)" .)