Uprising of students fixed for end of day (6)
I believe the answer is:
sunset
'end of day' is the definition.
(I've seen this before)
'uprising of students fixed' is the wordplay.
'uprising of' is a reversal indicator (I've seen 'uprising' mean this).
'students' becomes 'nus' (I've seen this in other clues).
'fixed' becomes 'set' ('set' can be a synonym of 'fixed').
'nus' backwards is 'sun'.
'sun'+'set'='SUNSET'
'for' is the link.
(Other definitions for sunset that I've seen before include "End of the day - maybe a bright one" , "'The dying of the 18'" , "When the light begins to fall below the horizon" , "Evening glow" , "When daylight fades" .)