締め切り
しめきり · shimekiri · JLPT N2 · noun
deadline
⏰ 締め切り = 締める (close) + 切る (cut): the point where submissions close and get cut off
締める means to close or tighten, and 切る means to cut. Together they name the hard cut-off moment when a deadline ends.
切 — 七 (phonetic) + 刀 (knife radical)
切 is a semantic-phonetic compound: 刀 'knife' gives the meaning of cutting, while 七 supplies the sound. The original sense was to slice or cut with a blade. From there it extended figuratively to 'close to' (as in pressed against) and 'urgent/earnest', as in 切实.