Possible Clues:

• Surviving no longer with blemish, having lost heart
• Current navigational device not accommodating first polar direction
• Surviving son leaves navigational instrument
• Navigation aid not opened, but still around
• Still living with former partner on square with half of 21 down
• Not destroyed or lost, as an old document
• Navigator's instrument with top knocked off still surviving
• Current navigator's device needs to start
• Still in being
• Surviving Texan shot twin, dismissing victory