保 guarantee/maintain

I guarantee that that HAIRY OBESE person can eat a tree in one mouthfull.

guarantee ★★★★☆
保 (guarantee/maintain ) + 証 (proof) = 保証 (guarantee)

conservative ★★☆☆☆ NEO
保 (guarantee/maintain ) + 守 (protect) + 主義 (- ism) = 保守主義 (conservative)

politically or morally conservative.

health insurance ★★☆☆☆
健康 (health) + 保険 (insurance) = 健康保険 (health insurance)

conserve, protect ★☆☆☆☆
保 (guarantee/maintain ) + 護 (defend) = 保護 (conserve, protect)

conserve, protect : used about protecting nature and the environment. But usually used with police protection (for snitches) or if you're escorting a lost child or drunk to the police box.

(BOOBOO: conservative person is　保守的な　（ほしゅてきな）　人)

a guarantor ★☆☆☆☆
保証 (guarantee) + 人 (person) = 保証人 (a guarantor)

a guarantor. This may not sound like a useful word to know, but if you ever come to Nippon, you'll need a Japanese guarantor. For pretty much everything- getting an apartment, a visa, etc. Usually it's your boss. So if you lose your job, your boss can kick you out of your house AND the country. It's a sort of share-cropper system!