Bloomer at university, interrupting endless row (5)
I believe the answer is:
lupin
'bloomer' is the definition.
(I've seen this before)
'at university interrupting endless row' is the wordplay.
'at university' becomes 'up'.
'interrupting' means one lot of letters goes inside another.
'endless' means to remove the last letter.
'row' becomes 'line' (I've seen this before).
'line' with its last letter taken off is 'lin'.
'up' going into 'lin' is 'LUPIN'.
(Other definitions for lupin that I've seen before include "Tall-spiked plant" , "Tall-spiked flower" , "Spiky flower" , "Colourful plant of pea family" , "Flower named from wolf" .)