New Yorker's behind acceptable British driver (6)
I believe the answer is:
button
'british driver' is the definition.
'button' can be an answer for 'driver' (I have seen 'Fast driver' mean 'button' so perhaps 'driver' could also mean 'button'). I'm not certain of the 'british' bit.
'new yorker's behind acceptable' is the wordplay.
'new yorker' becomes 'butt' (I can't explain this - if you can you should give a lot more credence to this answer).
'behind' says to put letters next to each other.
'acceptable' becomes 'on' (as opposed to not on, unacceptable).
'butt'+'on'='BUTTON'
Can you help me to learn more?
(Other definitions for button that I've seen before include "Worthless, they say" , "closer" , "On-screen control" , "Disc for pushing, fastening" , "Tot bun up for a fastener" .)