Second university student wasn't honest and got tainted (7)
I believe the answer is:
sullied
'tainted' is the definition.
('sully' can be a synonym of 'taint')
'second university student wasn't honest' is the wordplay.
'second' becomes 's' (common abbreviation).
'university' becomes 'U' (abbreviation for university).
'student' becomes 'L' (as in L-plates for learner drivers).
'wasn't honest' becomes 'lied' (told a lie).
's'+'u'+'l'+'lied'='SULLIED'
'and got' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for sullied that I've seen before include "Defiled" , "Stained or blemished as reputation may be" , "Made dirty" , "Disgraced, being ill-used" .)