Agile mammal of Asia, Europe and North America whose fur is highly valued (6)
I believe the answer is:
marten
(Other definitions for marten that I've seen before include "Weasel-like animal with thick soft fur" , "forest-dweller" , "Animal - rat men (anag)" , "Weasel-like mammal of forests" , "Furry carnivore, maybe of pine woods" .)