Awful bores at university become more realistic (5,2)
I believe the answer is:
sober up
'become more realistic' is the definition.
('sober up' can be a synonym of 'become more realistic')
'awful bores at university' is the wordplay.
'awful' indicates anagramming the letters.
'at university' becomes 'up'.
'bores' with letters rearranged gives 'sober'.
'sober'+'up'='SOBER UP'
(Other definitions for sober up that I've seen before include "Get real" , "Become less drunk" , "become serious" , "What you do when drink wears off" .)