Assume position with university behind schedule (9)
I believe the answer is:
postulate
'assume' is the definition.
(I've seen this before)
'position with university behind schedule' is the wordplay.
'position' becomes 'post' (synonyms).
'with' is a charade indicator (letters next to each other).
'university' becomes 'U' (abbreviation for university).
'behind schedule' becomes 'late' (running late).
'post'+'u'+'late'='POSTULATE'
(Other definitions for postulate that I've seen before include "That which is assumed" , "Put forward" , "Let sap out in order to claim something" , "Assume as axiom" , "Take for granted or lay down as self-evident" .)