Rarely standalone in modern speech. Lives mostly in compounds: 拘留 ('detain'), 拘束 ('restrained'), 拘谨 ('stiff, prim'), and the set phrase 不拘小节 ('not bothered by small details').
The hand radical on the left tells us 拘 is something done with the hands: grabbing, restraining, holding back. It anchors the meaning and indexes 拘 with 拿 grab, 抓 seize, 押 detain, 捕 catch - all hand-action verbs of capture and control.
句 supplies the sound jù shifting to jū, a clean tone drop. Its inner 口 wrapped by 勹 originally pictured something bent or hooked - a faint hint of crookedness fitting the idea of being constrained. The same phonetic includes 钩 hook, 苟 careless, 狗 dog.