Cold-blooded one (7)
I believe the answer is:
reptile
'cold-blooded one' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for reptile that I've seen before include "Turtle, for example" , "Turtle or snake say" , "Lizard, for example" , "Cold-blooded beast" , "Somebody grovelling" .)