Somewhat naive error — change direction (4)
I believe the answer is:
veer
'change direction' is the definition.
(I've seen this before)
'somewhat naive error' is the wordplay.
'somewhat' indicates the answer is hidden within the clue.
'VEER' is hidden in the letters of 'naive error'.
(Other definitions for veer that I've seen before include "Change direction abruptly" , "Deviate" , "Change direction sharply" , "Change direction or course, like wind" , "Sudden direction change" .)