sickle, stay, remain
剳 is a rare kanji with meanings that do not clearly connect: a sickle (a cutting tool) and the ideas of staying or remaining. The link between these senses is unclear, so treat its meaning as uncertain.
The exact historical development of 剳 is uncertain. It visually combines 荅 (a plant-related component) with 刂 (knife), but whether this reflects a true phono-semantic origin or a later corruption is unclear.
The left side 荅 looks like a plant with a mouth 口 under a grass crown ⺾, and the right side 刂 is a knife. Picture using a sickle-shaped knife to cut plants, but also imagine the plant stubbornly staying put, refusing to be cut.
For トウ, imagine a sickle that makes a toe-curlingly sharp cut: toe -> トウ, and the sickle stays in your hand as you work.