鞦

A phono-semantic compound composed of:

革 (leather) — semantic component, indicating straps or leather equipment;

秋 — phonetic component, indicating the sound (추 / qiū). The character originally described leather straps used in harnessing animals, such as those connected to a saddle.
Semantic development: - leather strap for saddles. - equipment related to riding animals. - swing (via compound 鞦韆);

추천 (鞦韆) — swing

鞦 is rarely used alone and mainly appears in the compound 鞦韆. The connection between saddle straps and swings likely comes from the idea of suspended movement using straps or ropes.
Related characters: 韆 — swing (paired in 鞦韆)

革 — leather

秋 — autumn (phonetic component)