Possible Clues:

• Girl's pen had broken
• Shewd, sharp
• There's one from Denmark about to be acid about her
• Favourite shrub of Apollo
• Author -- du Maurier
• Small shrub, fem. name
• ''Rebecca'' author du Maurier
• Nymph's laurel is hardy
• Laurel is a girl's name
• Young woman who became 23 had pen specially presented