Possible Clues:

• Search taking road back to border
• Clear out (a waterway)
• Revolutionary director heading, for example, back to do some work down the Shannon
• Doctor with blade and scoop
• Clean a canal, say
• Deepen a canal, in a way
• Clear a river bed
• Director general welcomes the German back from Spain to do some work on ocean liner
• To sprinkle with sugar is a drag
• Deepen a waterway delta and river bank?