Cold cubes (3)
I believe the answer is:
ice
'cold cubes' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ice that I've seen before include "If it's thin, skating on it can be dangerous" , "Precious stones" , "Winter formation" , "Do cake decoration" , "Frozen water; kill (slang)" .)