Philistine, a broadcaster with the university? Unbelievable! (1,3,3)
I believe the answer is:
i ask you
'unbelievable' is the definition.
(phrase used to show you can't believe something)
'philistine a broadcaster with the university?' is the wordplay.
'philistine' becomes 'I' (where the crossword setter is 'Philistine').
'broadcaster' becomes 'sky' (Sky is a television company).
'with' is a charade indicator (letters next to each other).
'the university?' becomes 'ou'.
'i'+'a'+'sky'+'ou'='I ASK YOU!'
(Other definitions for i ask you that I've seen before include "Exclamation of annoyance" , "Heavens" , "really!" , "Would you believe it!" , "how ridiculous is that?" .)