Related Clues:

• Flat bottom?
• Shell occupant
• Only it is under a foot
• See 4
• Noisy insect put off shy person
• Fish gets trodden on
• A swimmer - the only one to be seen
• Unique piece of footwear
• Nearly grip a shellfish
• One fish
• Shellfish left in river
• Mollusc left in river
• Just one - fish
• Fish - alone!
• Fish - only