Possible Clues:

• Become bony?
• Harden hearts of those lasses, pacifist pussycats
• Old saints, if meeting heresy, ultimately become rigid
• Cross, if Yorkshire holds become fixed
• Lose flexibility
• Become hardened
• Turn into fossil? Most of fossil badly done, ending in ignominy
• Order aboard with half of 21 down to do something with the boneheads
• Wartime intelligence agency, for your information, affected job of bonesetters
• Rouse stiffly off and on and become rigid