Possible Clues:

• Main vessel of a sea-going line
• Largest store in a chain
• Chief one in group points out joint
• An organisation's most important thing
• Best of its kind; admiral's craft
• Best or most important of its kind
• Pre-eminent fighter stays behind joint
• The USS Enterprise, e.g.
• Flowers and fruit, the finest specimen
• Plants fruit, showing a most important craft