Small mammal with reddish-brown fur and an elongated body (6)
I believe the answer is:
weasel
(Other definitions for weasel that I've seen before include "Animal; sly person" , "Old jingle 'Pop goes the . . . . . .'" , "Boggle" , "Carnivore; treacherous person (colloq.)" , "This small mammal saw eel" .)