USA, 1826, as ‘to flog somebody like seven bells’—to give a severe beating to somebody—‘seven’ is perhaps simply an arbitrary intensifier—cf. phrases such as ‘like seven bells half-struck’ (‘with as much speed as possible’) and ‘to blow seven bells’ (‘to blow a violent gale’)
USA, 1924—a questionable or unorthodox practice that has long been established—from literal uses (19th century onwards) referring to former Spanish colonies in America
to make bigger or greater, to enlarge—UK, 1884, as a translation of ancient Greek ‘μεγαλύνειν’ as used in the Acts of the Apostles, 5:13—recoined in 1996 in the U.S. animated television series The Simpsons
(literally) to formally agree to something by signing an official document—(figuratively) to make a firm commitment about something—USA, 1900s, in reference to life-insurance contracts
highly convincing circumstantial evidence—USA, 1862—ascribed to Henry David Thoreau—refers to the practice of surreptitiously diluting milk with stream-water
USA, 1930—a rhetorical question calling attention to a non-sequitur or irrelevant statement or suggestion made by another person—one of the phrases built on the pattern ‘what has that got to do with the price of ——?’
USA, 1969—the phrases ‘off the radar’, ‘under the radar’ and ‘below the radar’ are used of something or someone that cannot be detected—the reference is to an aircraft flying too low to be detected by a radar