Possible Clues:

• Basic seasoning
• It's labeled S, not P
• Sodium chloride
• Shaker contents
• It adds zest to meals for sailor on board
• Girl breaks pill to form white powder
• Time taken by qualified sailor to get item on board
• Tipsy British taste all the contents of cellar
• Girl walled in by stone slab which is put in cellar
• Seasoning for meal