鎖
サ, くさり, とざ.す
chain, irons, connection
JLPT1 G7 S18 F1250
The right-hand element# is 小 small + 貝 bivalve shell → small shells, pierced and strung together (compare 貫 and 朋). 鎖 adds 金 metal → small loops of metal linked in a *chain* → *shut*; *close* (← close links in creating a chain).
[Full Kanji Etymology List]