If only some writers could get their hands around these two words!

Clenched means any of the following:
• To curl one’s fingers into a tight ball, as in Jane clenched her fists when the airline told her she’d been bumped from the plane for Los Angeles.
• To press one’s teeth together in anger, as in Dawn clenched her teeth when the airline told her the flight to New York City was delayed.
• To grasp something hard with the hands or teeth, as in Melissa clenched the her suitcase handle when the flight attendant said she’d have to check it for her flight to Chicago.

Clinched means to confirm or settle, as in Laurie clinched the business deal with the San Francisco company.

An easy way to remember the two: Clench has to do with hands and teeth, usually responding in anger, while clinch indicates something that will bring happiness occurred.