Uninterrupted flow of traffic (4,5)
I believe the answer is:
free trade
This might be a double definition.
'uninterrupted flow' is the first definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'traffic' is the second definition.
(thesaurus)
'of' acts as a link.
Can you help me to learn more?
(Other definitions for free trade that I've seen before include "Unregulated commerce" , "International commerce without government interference" , "International commerce without restrictions" , "Interchange of commodities without hinder" .)