Related Clues:

• Requiring extra postage, say
• Hard to handle
• Herculean
• Teeming (with)
• Requiring great effort
• Difficult to carry, in a way
• "Tough day, ___?"
• Hard to carry
• Hard to tote
• Strenuous
• Word with duty or set
• Punishing
• Emotionally tough to take
• Of great weight
• Difficult, laborious