Briefly, certain academic success better (7)
I believe the answer is:
surpass
'better' is the definition.
(thesaurus)
'briefly certain academic success' is the wordplay.
'briefly' means to remove the last letter.
'certain' becomes 'sure' ('sure' can be a synonym of 'certain').
'academic success' becomes 'pass' (pass is a kind of success. I am not sure about the 'academic' bit.**).
'sure' with its final letter taken away is 'sur'.
'sur'+'pass'='SURPASS'
Can you help me to learn more?
(Other definitions for surpass that I've seen before include "eclipse visible" , "Be better than (own best)" , "Outstrip" , "Outdo" , "Go one better" .)