Possible Clues:

• Sugar syrup
• Set in theatre, a Cleopatra's sweet stuff
• Dark viscous 11
• Saplike stuff from a chlorine's absorption by woody plant
• That's sticky enough to make a cat reel
• Shake claret to a point where it becomes a thick syrup
• Sentimentality that Carroll's sisters had to live with
• Molasses relative
• In theatre, a cleaner displays over-sentimentality
• Cloying stuff in new production of 'Electra'