Did it contribute to the snarling of the old-time traffic? (7)
I believe the answer is:
growler
'traffic?' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for growler that I've seen before include "Unfriendly dog" , "Iceberg" , "Perhaps bear" , "Dog perhaps" .)