Traffic jam cause, often (10)
I believe the answer is:
bottleneck
(Other definitions for bottleneck that I've seen before include "Traffic restriction" , "Congestion" , "Constricted place" , "Traffic jam" , "Constricted section of road" .)
I believe the answer is:
bottleneck
(Other definitions for bottleneck that I've seen before include "Traffic restriction" , "Congestion" , "Constricted place" , "Traffic jam" , "Constricted section of road" .)