They usually lead to the quarry (6)
I believe the answer is:
spoors
'they' is the definition.
Both the definition and answer are plural nouns.
Maybe you can see an association between them that I don't see?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for spoors that I've seen before include "Hunters follow them when pursuing game" , "What the hunter follows in pursuing game" .)