Related Clues:

• Sanctum or circle preceder
• Adjective with Baltimore's harbor
• ''Tube'' lead-in
• City or tube preceder
• ''I'm __ human''
• -- tube
• Private ... or a hint to the words spelled by the circled letters
• ''The ___ Sanctum''
• ___ ear
• Word before a discounted price, perhaps
• Word after ''Exit''
• The ''O'' in SRO
• Adjective with ''ear'' or ''tube''
• "This is __ a test"
• See 24 Across