Outstanding university in Delaware (3)
I believe the answer is:
due
'outstanding' is the definition.
(an outstanding debt is due)
'university in delaware' is the wordplay.
'university' becomes 'U' (abbreviation for university).
'in' means one lot of letters goes inside another.
'delaware' becomes 'DE' (abbreviation).
'u' inserted inside 'de' is 'DUE'.
(Other definitions for due that I've seen before include "Required; proper" , "Unpaid or expected" , "Escort" , "Owed as a debt" , "imminent" .)