Western crew makes impact (6)
I believe the answer is:
weight
'impact' is the definition.
(I know that weight is a type of bias)
'western crew' is the wordplay.
'western' becomes 'w'.
'crew' becomes 'eight' (an eight-person rowing team).
'w'+'eight'='WEIGHT'
'makes' is the link.
(Other definitions for weight that I've seen before include "Heavy object" , "Relative heaviness" , "Something to lose" , "Significance" , "Importance, heaviness" .)