Be a standout (4)
(Other definitions for star that I've seen before include "A night light?" , "Brilliant person" , "Celebrity's" , "Celebrity in the world of entertainment" , "Public figure" .)
(Other definitions for excel that I've seen before include "Outrival" , "surpass all others" , "Do particularly well" , "Do exceedingly well" , "Be highly proficient" .)