Possible Clues:

• Agamemnon's son
• Ring about scenery put up for Euripides drama
• Son of Clytemnestra and Agamemnon
• See sort that could turn out murderer in mythology
• Classical matricide finds drug in fashion stores
• Matricidal son of Clytemnestra
• Matricide beheaded enemies without respite
• Son of Agamemnon taking ecstasy into the woods, heading off
• Hero of 20-Across
• Mythological brother of 63-Across