buckle

Entry Definition
s/he, it comes apart or buckles and collapses (e.g., rafter, chair under too much weight)
s/he, it comes apart or buckles and collapses (e.g., rafter, chair under too much weight)
it buckles due to heat
snap, clasp, buckle; coat hanger
s/he scares h/ causing h/ knees to get wobbly or buckle