Girl’s university in the south-east (3)
I believe the answer is:
sue
'girl's' is the definition.
(girl's name)
'university in the south-east' is the wordplay.
'university' becomes 'U' (abbreviation for university).
'in the' indicates putting letters inside.
'south east' becomes 'SE' (abbreviation).
'u' placed within 'se' is 'SUE'.
(Other definitions for sue that I've seen before include "Take legal action against (someone), girl's name" , "Begin legal proceedings against" , "Seek legal redress" , "Appeal" , "The girl to take to court" .)