Disapprobation over simple-minded besieging University (5)
I believe the answer is:
odium
'disapprobation' is the definition.
(I've seen this before)
'over simple-minded besieging university' is the wordplay.
'over' becomes 'o' (cricket abbreviation**).
'simple-minded' becomes 'dim'.
'besieging' is an insertion indicator.
'university' becomes 'u'.
'dim' placed around 'u' is 'dium'.
'o'+'dium'='ODIUM'
(Other definitions for odium that I've seen before include "Inability to abide someone" , "Disgrace or contempt" , "Antipathy" , "Loathing, contempt" , "Offensiveness" .)