Related Clues:

• Get blocked up
• Reporter's source, at times
• Unexpected info source
• Folk dancer's shoe, perhaps
• Air problem
• Not hold water, say
• Puddle producer
• Dutch shoe
• Radiator problem
• Footwear that's hard to run in
• Be less than watertight
• Tell anonymously
• Scuba diver's worry
• Block the pipes
• Become blocked