I bought a leather rig off a clearance page a few years back, something like 70% off because it was an older colorway they were phasing out. The warranty held up fine. About two years in the stitching on one of the pouches let go and they repaired it no questions asked. The warranty follows the construction of the belt, not the price you paid, so clearance stock gets the same coverage as full price stuff in my experiance.
That said, there are a couple things worth checking before you click buy. First, read the listing wording carefully. If it says 'final sale' or 'as-is' anywhere, that changes things. A plain 'clearance' tag ussually just means they're moving old inventory. Second, save a screenshot of the listing showing the warranty claim, because if it ever comes down to it you want proof of what was advertised when you bought it. Third, if you really want peace of mind, email the maker and ask directly wheather clearance items carry the full warranty. Decent shops answer that in a day and it takes all the guesswork out.
The other thing to know is that deep markdowns on leather gear are often cosmetic stuff. Scars in the hide, off colors, a stamped logo that's slightly crooked. None of that affects how it wears. Leather is forgiving like that. What actually kills a tool belt is thread and rivets, and those are the same on clearance stock as anything else. Honestly the bigger risk in your situation isn't the warranty, it's fit. Buying online means you can't feel the leather or check the pouch layout against how you actually work. Measure your waist over whatever you wear on the job and compare it to their sizing chart, not your pants size. A belt that fits right breaks in and lasts a decade. One that doesn't will fight you every day no matter what it cost.