Cleaner accepting one post at university (5)
I believe the answer is:
chair
'post at university' is the definition.
(chair can mean a professorship)
'cleaner accepting one' is the wordplay.
'cleaner' becomes 'char' (charwoman is a type of cleaner).
'accepting' indicates putting letters inside (inserted letters are accepted).
'one' becomes 'i' (Roman numeral).
'char' going around 'i' is 'CHAIR'.
(Other definitions for chair that I've seen before include "Lead" , "What professor has" , "Academic position" , "Single seat" , "Professorship" .)