"Ivories" (4)
I believe the answer is:
keys
'ivories' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for keys that I've seen before include "Lower House of the Isle of Man parliament" , "Lock openers" , "Low islands, sycamore fruits" , "Solutions" , "Openers - low-lying islands" .)