Leaving car briefly for teatime snack (6)
I believe the answer is:
parkin
'teatime snack' is the definition.
(type of gingerbread)
'leaving car briefly' is the wordplay.
'leaving car' becomes 'parking'.
'briefly' means to remove the last letter.
'parking' with its final letter removed is 'PARKIN'.
'for' is the link.
(Other definitions for parkin that I've seen before include "Soft gingerbread" , "Ginger oatmeal cake" , "Scottish biscuit" , "Gingerbread made with oatmeal and treacle" , "Type of gingerbread" .)