Clue: Evergreen Shakespearean killer, not half: 'Ides isn't tragic' (10)
Answer: ASPIDISTRA
Explanation: Definition: Evergreen
A charade of ASP ('Shakespearean killer', Antony and Cleopatra -at least, Cleopatra) plus ID IS TRA ('not half: **ID**es **IS**n't **TRA**gic').