張り切る
はりきる · harikiru · JLPT N2 · verb-godan
to be in high spirits
🔥 張 = stretch, 切 = cut: stretch yourself tight, like a bowstring ready to fire, to be full of vigor
張る (haru) means to stretch taut, and 切る (kiru) means to cut through or go all the way. Together they describe pulling yourself fully taut, ready to go at full strength.
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.