Related Clues:

• Snake to stop this on road
• Roofing material poisonous thing? Stop!
• Constituent of tar: part primarily used by people
• Tarry substance
• Natural bituminous material used for making pavements, etc
• Turnpike topper
• Support for transport workers led by one in energy unit
• Corporation taken in by good French pitch
• Regularly pass up rest to get the black stuff
• A winding path's blocked by large surface material
• Road surfacing while parking has to stop
• Black stuff created by queen's poisoner before arrest
• Round a lake, relaid paths with this, perhaps
• Cleopatra's unspoken last words surfacing in America?
• Area parking hard, restricted by tar surface