| SPIRAL | Shape of a winding staircase, or, the helical structure of DNA (6) |
| WELL | A shaft or indent, be it a stone-lined hole for drawing water, an opening in the centre of a winding staircase or a depression in flour to hold milk/eggs (4) |
| THREAD | A fibre or filament; the theme running throughout a book, debate etc; or, the helical part of a screw (6) |
| CRICK | Biologist who discovered the helical structure of DNA with James Watson (5) |
| RUNNER | Strip of carpet for a staircase; or, a person who purchases antiques on behalf of a dealer (6) |
| WATSON | James -; the co-discoverer with Francis Crick of the doublehelical structure of DNA (6) |
| NEWEL | What is the central pillar of a winding staircase? (5) |
| TWISTS | Unexpected developments or revelations in novels, plays or films; spiral-shaped wineglass stems; helical batons of baked bread or pastry; or, silk threads (6) |
| NEWELS | Winding staircase posts |
| SPRING | Helical device described in Hooke's law; or, a fountainhead (6) |
| SCREWS | Fasteners with helical threads; twists of paper; or, ship propellers (6) |
| RAMP | From "clamber, climb, crawl, creep", an incline or slope; an upward bend in a bannister; a swindle involving exorbitant prices; a mobile staircase; or, a sleeping policeman (4) |
| HANDRAIL | A railing at the side of a staircase or balcony to prevent people from falling. |
| GUARDRAIL | A safety barrier at the side of a staircase or road (9) |
| ROSALIND | As an expert in crystallography at King's College London, she made a crucial contribution to the discovery of the structure of DNA (8,8) |
| FRANKLIN | As an expert in crystallography at King's College London, she made a crucial contribution to the discovery of the structure of DNA (8,8) |
| DOUBLEHELIX | The form of the molecular structure of DNA |
| VOLUTE | Helical (6) |
| BALUSTRADE | The railings of a staircase or balcony (10) |
| FRANCISCRICK | Codiscoverer of the structure of DNA: 2 wds. |
