Gives gears thrashing — like some white van drivers? (10)
I believe the answer is:
aggressive
'like some white van drivers?' is the definition.
(white van drivers are stereotypically aggressive)
'gives gears thrashing' is the wordplay.
'thrashing' is an anagram indicator (I've seen this in other clues).
'gives'+'gears'='givesgears'
'givesgears' with letters rearranged gives 'AGGRESSIVE'.
(Other definitions for aggressive that I've seen before include "Vigorous" , "Showing anger" , "Combative - pushing" , "Pushy" , "Forceful" .)