Instrument, somewhat forgotten, rockets to the sky (8)
I believe the answer is:
cornetto
'the sky' is the definition.
Both the answer and definition are singular nouns.
Perhaps there's an association between them I don't understand?
'instrument somewhat forgotten rockets' is the wordplay.
'instrument' becomes 'cornet' (cornet is a kind of instrument).
'somewhat forgotten rockets' becomes 'to' (I can't explain this - if you can you should give a lot more credence to this answer).
'cornet'+'to'='CORNETTO'
'to' is the link.
Can you help me to learn more?
(Another definition for cornetto that I've seen is " historical wind instrument".)