Again hiding a prejudice (4)
I believe the answer is:
bias
'prejudice' is the definition.
('bias' can be a synonym of 'prejudice')
'again hiding a' is the wordplay.
'again' becomes 'bis' (I've seen this in other clues).
'hiding' is an insertion indicator.
'bis' placed around 'a' is 'BIAS'.
(Other definitions for bias that I've seen before include "One-sided prejudice" , "Large city in Florida" , "(Bowls) irregular shape" , "One-sided inclination" , "A leaning or prejudice" .)