"Rocks” (3)
'rocks' is the definition.
(both can informally mean diamonds)
This is all the clue.
(Other definitions for ice that I've seen before include "A state of water" , "Winter formation" , "Cubes in a drink" , "It's cold and slippy" , "Slippery surface" .)
(Other definitions for fists that I've seen before include "Boxer's punchers" , "addition to arms?" , "Doubled up hands" , "Fighting tools" , "bunches of five" .)