This writer has got upset with student's wickedness (4)
I believe the answer is:
evil
'wickedness' is the definition.
(I know that wickedness can be written as evil)
'this writer has got upset with student's' is the wordplay.
'this writer has' becomes 'ive' (I can't justify this - if you can you should believe this answer much more).
'got upset' is a reversal indicator (I've seen 'getting upset' mean this).
'with' says to put letters next to each other.
'student' becomes 'l' (as in L-plates for learner drivers).
'ive' backwards is 'evi'.
'evi'+'l'='EVIL'
Can you help me to learn more?
(Other definitions for evil that I've seen before include "Maleficent" , "Malignant" , "Morally reprehensible" , "very naughty" , "Live badly for badness" .)