Related Clues:
- Extracts metals by heating
- Proof jobs
- Runs a blast furnace
- Corrects a manuscript
- Additions and subtractions, of a sort
- Dig further down
- Reviews and corrects text
- Works for People, perhaps
- Bird on river to get more down
- Make more profound
- River needing swan to make room for more water
- Make (colour) darker
- Get stronger place of confinement south of river
- Fixes a column, say
- Cleans up text