Bigoted, as certain could be (9)
I believe the answer is:
sectarian
'bigoted' is the definition.
('sectarian' can be similar in meaning to 'bigoted')
'as certain could be' is the wordplay.
'could be' indicates anagramming the letters.
'as'+'certain'='ascertain'
'ascertain' with letters rearranged gives 'SECTARIAN'.
(Other definitions for sectarian that I've seen before include "Denominational" , "Concerning one group" , "Prejudiced against other religions? So ascertain" , "Of a religious faction" , "from an unorthodox group" .)