No Parking zone will wear out and get covered in clay (8)
I believe the answer is:
clearway
'no parking zone will wear out' is the definition.
I can't tell whether this definition defines the answer.
'get covered in clay' is the wordplay.
'get' becomes 'clear' (clearing is a kind of getting).
'covered in clay' becomes 'way' (I can't justify this - if you can you should give a lot more credence to this answer).
'clear'+'way'='CLEARWAY'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for clearway that I've seen before include "area where you can't stop" , "where one must keep going" , "thoroughfare" , "Stopping is not allowed on this road" , "No parking on it during certain hours" .)