A cut involved university entrance hall (6)
I believe the answer is:
atrium
'entrance hall' is the definition.
(I've seen this before)
'a cut involved university' is the wordplay.
I cannot really understand how this works, but
'a' is present in the answer.
'university' could be 'u' (abbreviation for university) and 'u' is found in the answer.
'cut' could be 'trim' (trim is a kind of cut) and 'trim' is found in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for atrium that I've seen before include "Central area in a building, open or glass-roofed" , "High central hall in large building" , "Central area in a building open to the sky" , "Roofed central court" , "An upper cavity in the heart" .)