Possible Clues:

• Slip out of place, as a disk
• Slip out of place (medical)
• Fall down with course in writing
• Medical word meaning to slip out of place
• A fall inside, but worker is bearing up well
• One that should be in going out due to mistake by expert
• It's not poetry your friend will come up in and sink there
• Even a professional might make a mistake and sink thus
• A professional may make a mistake that will lead to a downfall inside
• Slippage, to an anatomist