Possible Clues:

• When a tile falls to the ground without good reason? (2,3,4,2,1,3)
• Without hesitation
• One way to go
• Instantly ... or how this puzzle's other three longest answers came about?
• How one gets alternative view from panorama immediately? (2,3,4,2,1,3)
• Anytime now
• With almost no provocation
• With only the slightest urging
• Immediately suggestive of boater going down? (2,3,4,2,1,3)
• When did race start in late 1800s? Without delay! (2,3,4,2,1,3)