pipe-opener

noun pipe-openers

1. A device for putting a hole in a pipe.
2. A device or mechanism for clearing obstructions in a pipe.
3. A practice event; a warm-up. They will note the doings of the favourite for some particular race, scanning him keenly and critically ; they will see how he takes his pipe-opener, or if he breaks down, or if he turns lame, or is absent from exercise.
4. figuratively A brisk walk or other aerobic exercise; a constitutional.
5. figuratively An example that serves as an introduction. That tale may have served as a pipe-opener, but one could not see its wood for its trees, so I threw it away.