Positioning yourself carefully back from the slot in the ceiling, and kneeling down, you give the tripwire a good yank.
There is a fairly loud click, almost metallic, and a rather large scythe comes arcing out of the right hand wall, slicing through the air with a loud whoosh. Though a fairly frightening sight, you were expecting almost exactly that, and it causes you little distress.
Tugging on the wire again has no effect, so you get to your feet and continue up the passage towards the room ahead.