Related Clues:

• Put one's foot down, when it's time to study
• A swimmer - the only one to be seen
• Unique piece of footwear
• One fish
• Act in walk-on parts?
• Step in tango requiring study
• Just one - fish
• Fish - alone!
• Fish - only
• Only - fish
• Top surface of step
• Fish - alone
• Put one's foot down!
• Moulded part of a tyre
• Step (heavily)