Unfairness improperly said to be by us (4)
I believe the answer is:
bias
'us' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'unfairness improperly said to be by' is the wordplay.
'unfairness improperly' becomes 'as' (I can't explain this - if you can you should believe this answer much more).
'said' indicates a 'sounds like' (homophone) clue.
'to be' becomes 'buy' (buying is a kind of being).
'by' says to put letters next to each other.
'buy' is a homophone of 'bi'.
'as' put after 'bi' is 'BIAS'.
Can you help me to learn more?
(Other definitions for bias that I've seen before include "One-sided prejudice" , "Prejudiced or weighted opinion" , "A leaning or prejudice" , "Prejudice, one-sidedness" , "Unfairly influence" .)