I signed up for about 2 years ago while catching a flight to DC from Seattle.
CLEAR is like “TSA PRE for VIPs.” Basically, you pay $100 annually and, at many — but not all-airports — you can jump the TSA PRE line. You also don’t have to show ID as your are scanned into the system, proving identity.
I had noticed, in the years before that, that more and more people were gaining TSA PRE. Same for Global Entry. I alone probably got 50 people to sign up for the former and maybe 20 for the latter. They are huge time savers. I’d say that CLEAR saves me 10-20 minutes on average on every other flight I take. Given how much I used to