Key material for piano makers (5)
I believe the answer is:
ivory
'key material' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for ivory that I've seen before include "Hard creamy-white dentine used for making ornaments" , "Substance of elephant's tusk" , "Key perhaps" , "Creamy colour" , "What may be carved" .)