Possible Clues:

• Rope to the mast is the chief support
• Something that plays the most important role in a particular group
• Support for parent during visit
• Support graduate, home on holiday?
• Chief supporter
• Support old lady during visit
• Unusual stamina? Yes — at the beginning giving chief support
• Anchor by source of current on river
• Support old woman during visit
• A rock where the sea's joining the river