Being overturned, declare bill is partly prejudiced (9)
I believe the answer is:
illiberal
'prejudiced' is the definition.
(thesaurus)
'being overturned declare bill is partly' is the wordplay.
'being overturned' is a reversal indicator.
'partly' indicates a hidden word (part of the clue is used).
'larebilli' is hidden in the letters of 'declare bill is'.
'larebilli' in reverse letter order is 'ILLIBERAL'.
(Other definitions for illiberal that I've seen before include "Intolerant; ungenerous" , "Narrow-minded" , "Intolerant; reactionary" , "Reactionary - mean" , "unenlightened?" .)