Likely to become successful (2-3-6)
I believe the answer is:
up-and-coming
'likely to become successful' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for up-and-coming that I've seen before include "Likely to become successful" , "Rapidly becoming successful" , "Promising to be successful" , "Beginning to become successful" .)