Clue: What pushy drivers do to gain entrance to estate (8)
Answer: TAILGATE
Explanation: Definition: What pushy drivers do
Another one I'm not sure about – a gate can be the entrance to an estate, so I suppose you could "tail" it to gain entrance, but that doesn't seem a very satisfactory explanation. *Thanks to crypticsue: it's a reference to the tailgate as the rear door of an estate car