Top down, German car leading (4,4)
I believe the answer is:
polo-neck
'top down german car leading' is the definition.
'polo neck' can be an answer for 'top' (I've seen this before). I am unsure of the 'down german car leading' bit.
'top down' is the wordplay.
'top' becomes 'polo' (polo top).
'down' becomes 'neck' (both can mean to finish a drink).
'polo'+'neck'='POLO-NECK'
Can you help me to learn more?
(Other definitions for polo-neck that I've seen before include "Type of jumper" , "Type of sweater collar" , "Pullover, high turned collar" , "A high turned-over collar on a jumper" , "High close-fitting collar" .)