Possible Clues:

• Lacking energy/enthusiasm
• Like a slug chewing the garlic?
• Lit charge exploded like a damp squib
• The garlic could make one sluggish
• A girl the different clubs become reluctant to move
• Slow to allow attack, borders gone, I see
• The garlic (anag.)
• Slow-moving glacier melts, engulfing the last shed
• Lacking pep
• Slow cooking required for the garlic