In favour of authorities restraining university press (6,6)
I believe the answer is:
fourth estate
'press' is the definition.
(synonyms)
'in favour of authorities restraining university' is the wordplay.
'in favour of' becomes 'for' (being for a particular cause).
'authorities' becomes 'the state'.
'restraining' is an insertion indicator.
'university' becomes 'U' (abbreviation for university).
'for'+'thestate'='forthestate'
'forthestate' going around 'u' is 'FOURTH ESTATE'.
(Other definitions for fourth estate that I've seen before include "Journalistic profession - press" , "addition to three-car family?" .)