Say nothing a sort of professor holds outrageous (9)
I believe the answer is:
egregious
'outrageous' is the definition.
(I've seen this before)
'say nothing a sort of professor holds' is the wordplay.
'say' becomes 'eg'.
'nothing' becomes 'o' (looks like zero - 0).
'a sort of professor' becomes 'regius'.
'holds' is an insertion indicator.
'o' inserted into 'regius' is 'regious'.
'eg'+'regious'='EGREGIOUS'
(Other definitions for egregious that I've seen before include "Insufferable" , "Notably bad" , "Outstanding, outrageous" , "Outstandingly villainous" , "Intolerable" .)