Star students on the way up (3)
I believe the answer is:
sun
'star' is the definition.
(Sun is an example)
'students on the way up' is the wordplay.
'students' becomes 'nus' (I've seen this in other clues).
'on the way up' says the letters should be written in reverse.
'nus' back-to-front is 'SUN'.
(Other definitions for sun that I've seen before include "Dawn riser" , "Star; newspaper" , "Centre of Earth's orbit" , "Star; paper" , "Hub of our planetary system" .)