Usually replacing a broken spoke isn’t a difficult task. That is, unless the offending spoke is a rear drive side spoke. In those cases, the rear cassette must be removed before the spoke can be replaced.
Unfortunately, removing the cassette requires a cassette lockring tool, wrench and chain whip. See Park Tool’s article Cassette Removal and Installation for more details.
Luckily, touring cyclists no longer need to carry shop tools or find themselves stranded with a broken rear drive side spoke thanks to a cool little tool from steintool.com called the Mini Cassette Lockring Driver. With it, a cassette lock ring can be easily removed and reinstalled without any other tools.
However, it took me a little time to understand how this unique tool works. So don’t wait until you need it to use it for the first time. Practice with the tool beforehand. The experience will be invaluable if you need to use it.