Possible Clues:

• Some remarkably rich words for a song
• Ira Gershwin's contribution
• Ira Gershwin line
• Number lines
• Piece piece?
• Words left one in flood of tears, upset
• Sir Tim's creation, part in comfortably rich West End theatre?
• Bit of a hit
• Three-quarters loaded onto empty lorry, relatively light
• Bit of a song's words