Thrive, be successful (7)
I believe the answer is:
prosper
I believe this clue is a double definition.
'thrive' is the first definition.
(I know that thrive can be written as prosper)
'be successful' is the second definition.
(thesaurus)
(Other definitions for prosper that I've seen before include "like Merimee, nominally" , "Succeed, flourish" , "Go well" , "Do well, be successful in life" , "Make good" .)