In favour of keeping university square (4)
I believe the answer is:
four
'square' is the definition.
(I've seen this before)
'in favour of keeping university' is the wordplay.
'in favour of' becomes 'for' (I've seen this before).
'keeping' means one lot of letters goes inside another.
'university' becomes 'u'.
'for' enclosing 'u' is 'FOUR'.
(Other definitions for four that I've seen before include "Two squared" , "Rowing boat; number" , "Number of Eliot Quartets" , "Set of bridge players?" , "Cardinal" .)