In the main, it provides the best way to stop (6)
I believe the answer is:
anchor
'stop' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I don't see?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for anchor that I've seen before include "Member of relay team" , "Last runner in relay race team" , "Device used to prevent vessel from drifting" , "It prevents a vessel from moving" , "Source of stability" .)