Possible Clues:

• "Goodies" singer
• 'Goodies' singer
• "Level Up" singer
• '1, 2 Step' singer
• One-named R&B singer with the hit '1, 2 Step'
• R&B artist with the 2004 hit '1, 2 Step'
• R&B singer of 'Oh' and 'Promise'
• One-named R&B artist
• Contemporary R&B diva
• R&B singer of "Oh" and "Promise"