They're spotted in casinos (4)
I believe the answer is:
dice
'they're spotted in casinos' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dice that I've seen before include "Make into chips" , "Cubes used in gambling" , "Gamble; cut into cubes" , "Numbered cube(s)" , "Gambling items" .)