Wise leader returns carpet to university (4)
I believe the answer is:
guru
'wise leader' is the definition.
(I've seen this in another clue)
'returns carpet to university' is the wordplay.
'returns' is a reversal indicator.
'carpet' becomes 'rug' (synonyms).
'to university' becomes 'u' (abbreviation for university).
'rug' backwards is 'gur'.
'gur'+'u'='GURU'
(Other definitions for guru that I've seen before include "Revered mentor" , "Spiritual guide" , "Influential expert" , "Hindu sage" , "Recognised expert in some field" .)