Nothing at all on university’s fake (5)
I believe the answer is:
false
'fake' is the definition.
(I know that fake can be written as false)
'nothing at all on university's' is the wordplay.
'nothing at all' becomes 'FA' (slang term - sweet Fanny Adams).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'university' becomes 'lse' (London School of Economics).
'fa'+'lse'='FALSE'
(Other definitions for false that I've seen before include "Not in accordance with fact" , "Bogus" , "Misleading" , "Sham" , "Artificial" .)