Tree radical on the left — pictograph of a tree, indexing 栓. It tells you this character names a wooden object: a peg, bolt, plug, or stopper. Same radical sits on 桩 stake, 椅 chair, 桥 bridge — everywhere wood is shaped into a thing.
Right 全 supplies the sound — quán shifts to shuān, a long phonological drift but the link is historical. 全 itself shows 人 over 王 (a person over jade), 'all kept whole.' Faint semantic bonus: a peg keeps things whole and secure when driven home into wood.
