Possible Clues:

• Is the letter enough to make father sheepish?
• Greek ram?
• Letter from Greek priest holding theological degree
• Greek alphabet letter
• Essayist, with Russian agreement, composes letter in Greek
• Teasing entertainer
• Initially, applicant with medical degree on day left a covering letter
• Letter that looks like a flipped y
• Doctor taken in by young man - a Greek character
• Dance, ignoring a Greek character