Distort, bias (4)
I believe the answer is:
skew
I believe this is a double definition.
'distort' is the first definition.
(I've seen this in another clue)
'bias' is the second definition.
(synonyms)
(Other definitions for skew that I've seen before include "Distorted, awry" , "Turn or place at an angle; bias" , "Slant, bias" , "Turn aslant" , "Not symmetrical" .)