Drunken rowdy lecturer dismissed on sovereign's return (5,4)
I believe the answer is:
lager lout
'drunken rowdy' is the definition.
'lecturer dismissed on sovereign's return' is the wordplay.
'lecturer' becomes 'l'.
'dismissed' becomes 'out' (I've seen this before).
'on' means one lot of letters go next to another.
'sovereign's return' becomes 'lager' (I can't justify this - if you can you should give a lot more credence to this answer).
'l'+'out'='lout'
'lout' put after 'lager' is 'LAGER LOUT'.
(Other definitions for lager lout that I've seen before include "Boozy yob" , "Aggressive young drunk" , "anti-social sort" , "Drinker behaving antisocially" , "Alcohol-fuelled youth" .)