Treatment of savant by university (5)
I believe the answer is:
usage
'treatment of' is the definition.
(I've seen this before)
'savant by university' is the wordplay.
'savant' becomes 'sage' (I've seen this before).
'by' is a charade indicator (letters next to each other).
'university' becomes 'u'.
'sage' after 'u' is 'USAGE'.
(Other definitions for usage that I've seen before include "Usual practice" , "Customary practice" , "Accepted or habitual practice" , "Custom - treatment" , "etiquette" .)