Possible Clues:

• Rodgers & Hart song
• Sad and low before noon, a rare occurrence
• Coloured lunar phenomenon, happens rarely
• Not usually once in such a shady doctor on in the sky
• Once in this, there's not a shade of 30 down
• Once in , as seldom happens
• Sounds as if this was blowing over a satellite
• Once in there, not of ten?
• Once in, this sounds as if it was blowing the doctor on
• Once in one is not of ten joined up