Related Clues:

• It's little matter
• Half the dictionary?
• Miniscule amount
• Tiny little bit
• Powerful mite
• Something to smash
• Label on the first of two file drawers, maybe
• Lepton's locale
• Greek I
• Teeniest Greek letter?
• Physicist's subject
• Small matter?
• Letter before kappa
• Small bit
• Bit of nuclear physics