Possible Clues:

• Brown flatfish
• A succulent flat-fish
• I am to be found in the locality, but all at sea and that's flat
• By the sound of it, that's where it's 11 across, and that's flat (6)
• Soft fabric to catch one fish
• In its stead I have fish
• One is in the locality, and that's flat
• Sounds as if it might be located on the seabed, and that's flat
• Sounds as if this locality is so flat
• A sound place