Possible Clues:

• A male, one in G and S, all-round character?
• Letter on a house used by 4-Across
• Greek character is back with good degree
• S, as in Socrates
• Character central to the writing of Aesop
• Foreign character's scar dermatologist finally removed
• Summation signifier, in math
• A classic car is back, of classic character
• Writer reflected over first Greek letter
• The eighteenth letter of the Greek alphabet