Possible Clues:

• Trial: it must establish contents?
• Revealing ritual
• A sure indication drunk has to set out
• Decisive check that may produce basic result?
• It has to -- in case holding that is seen as an indication
• Evaluation based on a single deciding issue
• List includes foremost Tempranillo grape juice from Spain - presumably, it will show a level of acidity
• Laboratory experiment, content of chemical it must establish
• Disputed titles will contain duty, providing definitive trial
• Indicator illuminated, has to set off