Upset about university student's bloomer (5)
I believe the answer is:
tulip
'bloomer' is the definition.
(I've seen this before)
'upset about university student's' is the wordplay.
'upset' becomes 'tip' (I've seen this in another clue).
'about' indicates putting letters inside.
'university' becomes 'u' (abbreviation for university).
'student' becomes 'l' (as in L-plates for learner drivers).
'u'+'l'='ul'
'tip' enclosing 'ul' is 'TULIP'.
(Other definitions for tulip that I've seen before include "It blooms in 11 down" , "Garden flower from bulb" , "Bulb producing a single showy flower" , "Liliaceous bulb" , "Flower - lit up (anag)" .)