Cowboy in west moved fast, not complacent in one transporting goods free of duty (8)
I believe the answer is:
wrangler
'cowboy' is the definition.
(wrangler is a kind of cowboy)
'west moved fast not complacent in one transporting goods free of duty' is the wordplay.
I cannot really understand how this works, but
'west' could be 'w' (abbreviation) and 'w' is present in the answer.
'moved' could be 'ran' (running is a kind of moving) and 'ran' is found in the answer.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for wrangler that I've seen before include "Ranch livestock handler" , "one is in charge of animals" , "One arguing" , "As a leading mathematician" , "One engaged in dispute - cowboy - Cambridge mathematician with a first-class degree" .)