The best replacement for clasp is tie bar.

The best alternatives to clasp are rated as following:
★★★★★  tie bar
★★★★  buckle
★★★★  grasp
★★★  clap
★★  lobster clasp
★  pinch clasp
★  spring clasp
  padlock style twist clasp
  slide
  not to clasp

Your alternative for clasp is not listed? Suggest!
Speaking about clasp, one probably shouldn't forget about safety chain.

Other search terms related to clasp and their ratings are:
★★★★★ safety chain
★★ chain
★★ end cap
extender
You have in mind a companion for clasp and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of clasp in all years. Click on graph for more.
clasp
tie bar
buckle