疗

Sickness radical wrapping the upper-left — a person lying on a bed, the cap for everything illness-related. Marks 疗 as belonging to the medical-treatment family (疾 disease, 病 illness, 痛 pain, 愈 healing). The sickness shed sets the scene of someone confined; the bottom phonetic gives the action that resolves it.

Inside 了 supplies sound and meaning. Sound: liǎo → liáo with a tone shift. Meaning: 了 means 'to finish, to complete' — exactly what a cure does to an illness. The traditional 療 used 尞 phonetic; PRC reform replaced it with the more compact 了, keeping the liáo reading and gaining a fitting 'complete the illness' semantic.