trono

Trono has a false seam in it, and it is a sharp one because the suffix it imitates is a real and common suffix. -On- makes fractions: duono is a half, triono a third, kvarono a quarter, and the pattern is regular enough that a learner reads -on- as a fraction on sight. Try it here and you get tr- plus "one part of", which is a fraction of nothing. There is no root tr-. Tron- is the whole root, borrowed once from Greek and never taken apart since.

The word carries the same metonymy as in English. A trono is the chair, but "the throne" also means the office and the person: li perdis la tronon is he lost the crown, not he lost the furniture. Krono sits beside it doing the same double work, which makes the pair a tidy little lesson in how political vocabulary gets built out of props.

Troni is a real verb - to sit enthroned, and by extension to preside over something, usually with a hint that the presiding is more decorative than useful. Surtroniĝi is to come to the throne and sentronigi is to depose, both assembled out of pieces you already have.