Follows the marks of an animal (6)
I believe the answer is:
tracks
'follows the marks of an animal' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tracks that I've seen before include "Rough paths; traces" , "Spoo" , "where they chase hares?" , "Trails" , "Marks or routes, of an animal say" .)