Possible Clues:

• Sharp, sour
• Having a sour or bitter taste
• Like citrus fruit
• Low on the pH scale
• Like vinegar or grapefruit juice
• Biting a lot of detectives, I see
• A branch of the police force, I see, is so cutting
• How a branch of the police, I see, gets biting
• Sharp tasting
• Sarcastic or sour