Related Clues:
- Put your foot down on 6 across
- Put your foot down on correspondence
- Show petulance
- Purchase that's canceled
- Really put one's foot down
- Symbol of approval
- Slam one's foot down
- One sticks to one's post
- Tread heavily (on an envelope?)
- Tread noisily
- Philatelist's item
- Bring foot down hard
- It is stamped on envelope
- Validation for a letter — tread heavily
- Brand of squash