Related Clues:

• See 2 Down
• Open-and-___ case
• Completely closed
• Sealed, say
• Not even cracked
• Securely sealed
• Thus it may get close
• Close to the South you get to 21 down
• How, perhaps, a call for silence may be said to have closed everything up
• It's said to be quiet when the window's closed over
• This is close
• Close with it
• O, that does not go over the pen
• Open's partner
• Sealed tight