Related Clues:

• Quarky item?
• Powerful particle
• Fermi's bit
• -- smasher (accelerator)
• Molecular component
• Power source
• The least bit
• Spring festival
• Electrolysis particle
• Small speck of dust
• 'Charge' missing from 18-, 20-, 55- and 61-Across, and 11- and 28-Down
• Smasher bit
• Dust speck
• No big thing
• Least little bit