University in Irish district wanting new hall (6)
I believe the answer is:
atrium
'hall' is the definition.
(I've seen this before)
'university in irish district wanting new' is the wordplay.
'university' becomes 'u' (abbreviation for university).
'in' indicates putting letters inside.
'irish district' becomes 'Antrim' (County Antrim).
'wanting' indicates named letters should be taken away (to want something can mean to lack it or need it).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'u' put into 'antrim' is 'antrium'.
'antrium' with 'n' taken away is 'ATRIUM'.
(Other definitions for atrium that I've seen before include "An upper cavity in the heart" , "Central hall or court" , "Um, I rat on the chamber of the heart" , "Central area in a building, open or with a glass roof" , "Entrance hall" .)