Related Clues:

• Toughen, as to hardship
• Tinker with
• Become hardened (to)
• Demonstrate flexibility
• Get used to (Var.)
• Harden: Var.
• Blend in
• Tune, for example
• Make immune
• Cause to become hardened to
• Make accustomed (to)
• Show elasticity
• Change, evolutionarily
• Keep up with the times
• Become acclimatized