Related Clues:
- Not openly shared
- Like passwords, ideally
- Undercover team briefly infiltrating group
- Something not to tell
- Uncommunicative soldier
- Hidden on top of cambium in wild trees
- With 37-Across, Election Day practice ... and a hint to this puzzle's theme
- Almost leak what shouldn't be leaked?
- Army man's retiring
- Those starting for every side today, with a skeleton in the cupboard
- Trade ___ (Coca-Cola's recipe, e.g.)
- It's meant to be kept
- Covert; classified
- Like Superman's alter ego
- Guarded against discovery