Possible Clues:

• Endure, long after date that's absolutely final
• Done when all other options have been exhausted
• Denoting final attempt
• Do-or-die
• Survive desert, a place of desperation
• Eleventh hour
• Desperate effort, of course, to get over the final obstacle
• Hold out, then abandon such a desperate defence?
• Desperate to survive axe
• Carry on with abandon - resistance ends here