Possible Clues:

• Letter between kappa and mu
• A letter for the Greek ram, perhaps
• Young man admits doctor gets a Greek letter
• It resembles an inverted V
• Wavelength symbol
• Greek letter whose lowercase indicates wavelength
• Greek letter resembling an upside-down V
• Letter resembling an inverted 'V'
• Brazilian dance ousting a Greek character
• Greek letter — am bald (anag)