Custom in university associated with wise man (5)
I believe the answer is:
usage
'custom' is the definition.
(I know that custom can be written as usage)
'university associated with wise man' is the wordplay.
'university' becomes 'u' (abbreviation for university).
'associated with' means one lot of letters go next to another.
'wise man' becomes 'sage' (sage is a kind of wise man).
'u'+'sage'='USAGE'
'in' acts as a link.
(Other definitions for usage that I've seen before include "Custom; practice" , "Habitual custom" , "management" , "Accepted or habitual practice" , "Usual practice" .)