Instrument next to piece of glass containing hard protective covering (10)
I believe the answer is:
cellophane
'covering' is the definition.
(cellophane is a kind of covering)
'instrument next to piece of glass containing hard protective' is the wordplay.
I cannot quite understand how this works, but
'instrument' could be 'cello' (cello is a kind of instrument) and 'cello' is found in the answer.
'piece' could be 'p' (abbreviation for Pawn) and 'p' is located in the answer.
'hard' could be 'h' and 'h' is found in the answer.
The remaining letters 'ane' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for cellophane that I've seen is " Thin transparent wrapping material".)