Possible Clues:

• Willow-bark extract
• Heart protector
• How A rips up in something for 10 across?
• One of 30 across may start to be the thing for a pain in the neck
• For a pain, Sir, that's the thing
• That's the very thing for a pain, Sir (7)
• Pain-relieving drug made in Paris
• Common analgesic drug
• Hopin' for relief when achin'
• Sip rain (anag.)