The preserve of drivers? (7,3)
I believe the answer is:
'of drivers?' is the definition.
The definition suggests a singular noun which matches the answer.
'the preserve' is the wordplay.
I cannot quite see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'preserve' could be 'jam' (jam is a kind of preserve) and 'jam' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for traffic jam that I've seen before include "Bottleneck on wheels" , "stuck in this" , "could make driver late" , "Vehicular snarl-up" , "Gridlock" .)