Possible Clues:

• Big adjustable spanner a boon to estuary's shipping
• Modify widget with borer and adjustable spanner
• *Landmark over the Thames
• Wrote about game, a fixture between two Thames boroughs
• Girder to be fixed outside with adjustable spanner
• River Thames crossing near St Katharine Docks
• Crossing over river to make tea around hilltop
• Get worried when diverted round front of busy London landmark
• One dragging newly-wed around grand sight in the capital
• Get worried, moving over British river crossing