Prejudice in book reported to be cut back (4)
I believe the answer is:
bias
'prejudice' is the definition.
(I know that bias is a more specific form of prejudice)
'in book reported to be cut back' is the wordplay.
'in' indicates putting letters inside.
'book' becomes 'b' (abbreviation for book).
'reported' becomes 'is' (I can't explain this - if you can you should give a lot more credence to this answer).
'to be' becomes 'am'.
'cut back' means to remove the last letter.
'b'+'is'='bis'
'am' with its final letter taken off is 'a'.
'bis' going around 'a' is 'BIAS'.
Can you help me to learn more?
(Other definitions for bias that I've seen before include "Unfairly influence" , "Prejudiced or weighted opinion" , "Spin" , "Inclination of prejudice" , "A leaning or prejudice" .)