Possible Clues:

• Junior swimmer continuously bearing left
• Glass eel
• Always catching lake fish when young
• Little fish always grabs line
• Young slippery fish
• Always take line to catch fish
• New slipper always left around? Quite the opposite!
• It's a little fishy so to revel with it
• Abusively criticise dropping one rising young swimmer
• Young swimmer, one going deeper having removed cap