Looking back, some declare Bill is intolerant (9)
I believe the answer is:
illiberal
'intolerant' is the definition.
('illiberal' can be a synonym of 'intolerant')
'looking back some declare bill is' is the wordplay.
'looking back' says the letters should be written backwards.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'larebilli' can be found hidden inside 'declare bill is'.
'larebilli' in reverse letter order is 'ILLIBERAL'.
(Other definitions for illiberal that I've seen before include "unenlightened?" , "Narrow-minded" , "Intolerant; reactionary" , "Intolerant; ungenerous" , "Reactionary - mean" .)