Possible Clues:

• Be hardened to be as R is here, it seems
• Accustom (someone to something)
• Guarantee 'Seconds out!' will lead to temper
• Toughen up in river
• Toughen up concerning cut by university
• Temper that results from keeping Julia primarily away from harm
• Become accustomed to
• Desensitize (to)
• Temper letter consumed by anger
• Cause to accept