Wall warts are not constant current devices, they're simple rectifiers. Just because the AC/DC adapter is capable of 1.25A doesn't mean it will be supplying 1.25A; that current is still dependant on the resistance of the radio, and will be self-limiting. As noted above, a lot of the AC/DC adapters are cheaply designed and rely on a specific resistance to put out their specified voltage, but it's not like it's going to put out 80V or anything, you're just taking maybe 10V out of an 8V supply, etc.
Unless this is a really expensive radio, I wouldn't think twice about using this charger with it.
