Possible Clues:

• Bitter start of a cruel epigram (recalling Baudelaire)
• A European said to be so bitter?
• Bitter starts for any cars easing round bend
• Genus of plants with berries initially bitter
• Bitter Republican absorbed in first-class book
• Bitter, in poetry
• Bitter a Belgradian reportedly supplied
• Brother up for supporting card sharp
• An Eastern European said to be bitter
• Bitter berries initially seen on tree