Answer: buckle

AnswerCrossword Clue
BUCKLEWord that can mean "join together" or "fall apart"
BUCKLEConcentrate, with "down"
BUCKLECollapse
BUCKLEClasp.
BUCKLEBelt closer
BUCKLEBelt feature
BUCKLEBend under pressure
BUCKLESeat belt feature
buckleto fasten with a buckle
buckleto bend
buckleto fasten one's belt, seat belt, or buckles
buckleclasp for two loose ends
buckleto set to work
buckleto bend or warp