Possible Clues:

• One of a number of children sequentially evident in Alcott tale
• Travel permit for a group of three
• Initially tennis rule included playing additional serve or three in a set
• Activate call for better service, part of multiple delivery
• Child of three allowed to go over first
• Travel permit for one arriving originally with two others
• One of three allowed to follow expedition
• One of three kids scattering litter round front of park
• One of three of a kind
• Rare birth