Woman radical on the left, the indexing radical. 婿 means son-in-law - the husband of one's daughter, defined entirely by the relationship to the woman of the household. The radical anchors 婿 alongside 妈 mother, 妹 younger sister, 姐 elder sister, 姑 aunt.
Right side 胥 supplies the sound - xū shifting to xù with a tone change. 胥 itself referred originally to a low-ranking official. The same phonetic drives 蝑 cricket and 醑 fragrant wine - a small but consistent xu family that locks the reading in memory.
