Hi Chrise and Rossim. Modus has finished and my stollen is on its third rise, so I'm back at the crossword. Thanks for your hints. Unfortunately, the penny hasn't dropped yet. I can't think of a large black cat unless it is one belonging to a witch.
I've already tried the fraction approach, but nothing is obvious to me. Is it a baking ingredient I've just had my hands in?
The penny has just dropped with theme!!!!!