Unequal (3-5)
I believe the answer is:
one-sided
'unequal' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for one-sided that I've seen before include "So denied being unfair or biased" , "Unfair or partisan - single dimension?" , "Unfair or uneven" , "Unfairly biased" , "Unfair, unequal" .)