drawbridge

noun

1. A hinged bridge which can be raised (to prevent its being crossed, as across a moat, or to allow watercraft to travel beneath it).

   “Near-synonym: bascule bridge”

   “I might jump an open drawbridge, or Tarzan from a vine / 'Cause I'm the unknown stuntman that makes Eastwood look so fine”

2. (attributive, figuratively)A tendency to provide only limited access.

   “drawbridge mentality”

   “I looked at her with wide eyes, and the drawbridge of her reserve fell instantly.”

   “"Yeah, some people have a drawbridge mentality,” remarks Barry.“They move to an island and then they think that nobody else should be let in after them. […]”

   “And He gave me the steps I needed to take to let down the drawbridge of my heart again.”

   “They push against the drawbridge of my mind, shaking me to the core.”