Known -- as is music? (5)
I believe the answer is:
noted
'known' is the definition.
(similar in meaning)
'as is music?' is the wordplay.
'as' becomes 'note' (I can't explain this - if you can you should give a lot more credence to this answer).
'is music?' becomes 'd'.
'note'+'d'='NOTED'
Can you help me to learn more?
(Other definitions for noted that I've seen before include "Toned (anag.)" , "Remarkable" , "Remarked - famous" , "Well known; registered" , "prominent" .)