Air of Naples can make you smile, with plenty of oxygen (1,4,3)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

definition: a Neapolitan ‘air’ i.e. a song [wiki] anagram of (smile OOO)*, with O (chemical symbol for oxygen) three times anagram indicator: ‘X can make you Y’ can mean ‘Y can be made from X’