Good student starts to overcome weariness and shine (4)
I believe the answer is:
glow
'shine' is the definition.
('glow' can be a synonym of 'shine')
'good student starts to overcome weariness' is the wordplay.
'good' becomes 'g' (abbreviation).
'student' becomes 'l'.
'starts to' suggests taking the first letters.
The initial letters of 'overcome weariness' is 'ow'.
'g'+'l'+'ow'='GLOW'
'and' is the link.
(Other definitions for glow that I've seen before include "Give out light without flames" , "Shine, maybe in dark" , "Steady radiance" , "Emanate light" , "Shine steadily and brightly" .)