Airports you've clinched?
How do you clinch an airport? Visit every gate? Take off or land on every runway? Using every taxiway would be quite unlikely unless you're the pilot and the ground controller cooperative.
Been on every direct scheduled flight from that airport to some other airport at least once?
I know this is over 5 years old, but for a few years, I could say I clinched every commercial airline route out of HSV in 2014, with 9 routes on 4 airlines. That changed as two new airlines appeared, vying for Orlando; I may have to work on that one day. I can also count Albany, Georgia (ABY) and Columbus, Georgia (CSG), since they each have one airline and a single destination. This was back when I lived in Florida.
The last two feel like clinching I-175 and I-375 in St. Petersburg.