Sledge-pulling dog (5)
I believe the answer is:
husky
'sledge-pulling dog' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for husky that I've seen before include "Dog used in polar expeditions" , "Arctic sled dog" , "hampered by frog?" , "Breed of Arctic dog" , "Sledge-pulling dog" .)