Related Clues:

• Attendance count, informally
• Smoke detectors
• Eskimos rub them
• Organs that sniff
• Busybodies' active organs?
• Pterodactyl features
• Organs of smell
• Olfactory organs
• On the face of it, they seem like 31 across without one
• On the face of it, the South has got involved with 30 across
• Sounds as if they get sent for the difference between Sion and session
• On the face of it they get sent, by the sound of it
• Sent through them, by the sound of it
• Going on ahead, see 3 down for them (5)
• They go on ahead to get 21 across, for instance