Possible Clues:

• One might dig this for what are, in short, in the fish
• What's dug are shortly to be in the fish
• Are shortly dug into the fish
• Excavation
• Cutting right into fish
• Fish caught right in the channel
• Re this dugout, one will have to economise (6)
• Keen worker no longer required to make ditch
• The sort of dugout that's not on the water but may have water in it
• French making new start to waterway