抠门 is the go-to colloquial word for 'stingy/cheap.' It's stronger and more judgmental than 节约 (frugal). 抠细节 means to obsess over details - it can be positive (meticulous) or negative (nitpicky).
扌 is the hand radical 手 in left-side form. It marks 抠 as a hand action, grouping it with 拉 (pull), 抓 (grab), and 挑 (pick) - here the fingertip motion of digging into a small space to scoop something out.
区 supplies the reading, drifting from qū to kōu along an old velar pair. The same phonetic surfaces in 躯 (body), 驱 (drive), and 殴 (beat), and the partitioned-space sense fits the act of picking inside a confined nook.
