Attend university party, initially the worse for wear (4-2)
I believe the answer is:
beat up
'the worse for wear' is the definition.
(I've seen this in another clue)
'attend university party initially' is the wordplay.
'attend' becomes 'beat' (to be at an event is to attend it).
'initially' suggests taking the first letters.
The initial letters of 'university party' is 'up'.
'beat'+'up'='BEAT-UP'
(Other definitions for beat up that I've seen before include "Slang for assault violently, belabour" , "mug" , "Dilapidated" , "Assault violently and injure" , "Assault violently, batter" .)