Exposes second-in-command at university upsetting virtuous type (4)
I believe the answer is:
outs
'exposes' is the definition.
(outing is a kind of exposing)
'second-in-command at university upsetting virtuous type' is the wordplay.
'second in-command' becomes 'o' (2nd letter of 'command').
'at' means one lot of letters go next to another.
'university' becomes 'U' (abbreviation for university).
'upsetting' says the letters should be written backwards.
'virtuous type' becomes 'st' (short for saint).
'st' backwards is 'ts'.
'o'+'u'+'ts'='OUTS'
(Other definitions for outs that I've seen before include "Forces to leave state of concealment, exposes" , "Reveals" , "Publicly exposes a person's secret nature" .)