Jeer Republican philistine (4)
I believe the answer is:
boor
'philistine' is the definition.
(thesaurus)
'jeer republican' is the wordplay.
'jeer' becomes 'boo' (I've seen this before).
'republican' becomes 'r' (abbreviation).
'boo'+'r'='BOOR'
(Other definitions for boor that I've seen before include "Rude, uncultured type" , "Lout" , "oaf" , "Rude, uncultivated person" , "Crude uncouth person" .)