Docking clamp
From Memory Alpha, the free Star Trek reference
A docking clamp or mooring clamp is a mechanical device by which starships are held in place while docked at space stations such as Deep Space 9. Ships are unable to leave until the docking clamps are released.
In 2369, Odo suggested that Deep Space 9 explode her mooring clamps so that Jaheel could not blow his ship apart when he was forced to stay due to the aphasia virus moving through the station. (DS9: "Babel")
In 2370, Kira Nerys ordered that the docking clamps not be released on Vedek Winn's ship, as Winn was carrying a known collaborator. (DS9: "The Collaborator")
Docking latches, structural devices aboard Galaxy-class starships used to connect the saucer section to the stardrive section, are sometimes referred to as docking clamps as they serve a similar purpose. (TNG: "Hollow Pursuits")
