勤

Right strength radical (Kangxi #19) - a stylised muscular arm or wooden plough. Carries the meaning: hard physical effort. Together with 堇's clay-working imagery the picture is of someone toiling over tough material, exactly the 'diligent, regular, hardworking' core of 勤. Same radical in 劳 (labour), 努 (exert), 助 (help), 动 (move).

Left phonetic 堇 - supplies the sound (jǐn drifted to qín, regular onset shift in this group). Originally depicted yellow sticky clay used for pottery, hence 'tough, hard-worked material.' Same phonetic anchors 谨 (cautious), 仅 (only), 馑 (famine), 槿 (hibiscus) - a tight family worth memorising together.