Term for structure of skeleton - a key material (5)
I believe the answer is:
ebony
'a key material' is the definition.
(I've seen this in another clue)
'term for structure of skeleton' is the wordplay.
'term for' says to take the final letters (the letter which terminates the word).
'of skeleton' becomes 'bony' (I can't explain this - if you can you should give a lot more credence to this answer).
The last letter of 'structure' is 'e'.
'e'+'bony'='EBONY'
Can you help me to learn more?
(Other definitions for ebony that I've seen before include "Dark hardwood" , "Hard wood used for black piano keys and in cabinetwork" , "Very dark black" , "'Hard, dark wood (5)'" , "hard stuff" .)