Slow mover (8)
I believe the answer is:
tortoise
'slow mover' is the definition.
(animal which moves slowly)
This is all the clue.
(Other definitions for tortoise that I've seen before include "Shelled animal" , "Slow-moving four-footed reptile - outraced the hare" , "Might this animal turn to Tories?" , "Mobile home owner?" , "Shelled creature" .)