Swerve suddenly (4)
I believe the answer is:
veer
'swerve suddenly' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for veer that I've seen before include "Deviate" , "Suddenly change direction" , "Change direction sharply" , "Swerve" , "Change direction or course, like wind" .)