Kind of financial proposal with no realistic chance of success
I believe the answer is:
get rich quick
'kind of financial proposal with no realistic chance of success' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for get rich quick that I've seen before include "Kind of scheme aimed at making fast bucks" , "Leading (dishonestly?) to easy prosperity" , "Wanting easy money" , "Designed for making easy money" , "Kind of financial proposal with no realistic chance of success" .)