The character 揣 has two everyday readings. As chuāi it means to tuck something into your clothes; as chuǎi it means to guess or size up, as in 揣测 and 揣摩. A third reading, chuài, survives only in a few rare bound words.
扌 is the left-side form of 手 (hand). 揣 is a verb of doing something with the hand: slipping an object into a pocket, or by extension weighing and guessing intent. The hand radical anchors all of these tactile senses.
耑 supplies the sound, drifted to chuāi. It is the older ancestor of modern 端 (end; tip), drawn as a sprout with roots. Same phonetic family: 端 extremity, 喘 to pant, 湍 rapids.
