A surgical instrument, comprising: a housing; a shaft extending distally from the housing; an end effector assembly coupled at a distal end of the shaft; a movable handle coupled to the housing; and a drive assembly operably coupling the movable handle and the end effector assembly, the drive assembly including: a drive member configured to translate through the shaft and relative to the end effector assembly to actuate the end effector assembly; characterised by a torsion spring including a first leg and a second leg, the first leg operably coupled to the movable handle and configured to translate longitudinally through the housing in response to movement of the movable handle relative to the housing, the second leg operably coupled to the drive member and configured to translate longitudinally through the housing in cooperation with the first leg to thereby transfer longitudinal movement thereof into longitudinal movement of the drive member when a force acting on the drive member is less than a threshold force, the second leg configured to remain in fixed position, thereby tensioning the torsion spring and retaining the drive member in fixed position, in response to longitudinal movement of the first leg when the force acting on the drive member is equal to or exceeds the threshold force. a housing; a shaft extending distally from the housing; an end effector assembly coupled at a distal end of the shaft; a movable handle coupled to the housing; and a drive assembly operably coupling the movable handle and the end effector assembly, the drive assembly including: a drive member configured to translate through the shaft and relative to the end effector assembly to actuate the end effector assembly; characterised by a torsion spring including a first leg and a second leg, the first leg operably coupled to the movable handle and configured to translate longitudinally through the housing in response to movement of the movable handle relative to the housing, the second leg operably coupled to the drive member and configured to translate longitudinally through the housing in cooperation with the first leg to thereby transfer longitudinal movement thereof into longitudinal movement of the drive member when a force acting on the drive member is less than a threshold force, the second leg configured to remain in fixed position, thereby tensioning the torsion spring and retaining the drive member in fixed position, in response to longitudinal movement of the first leg when the force acting on the drive member is equal to or exceeds the threshold force. a drive member configured to translate through the shaft and relative to the end effector assembly to actuate the end effector assembly; characterised by a torsion spring including a first leg and a second leg, the first leg operably coupled to the movable handle and configured to translate longitudinally through the housing in response to movement of the movable handle relative to the housing, the second leg operably coupled to the drive member and configured to translate longitudinally through the housing in cooperation with the first leg to thereby transfer longitudinal movement thereof into longitudinal movement of the drive member when a force acting on the drive member is less than a threshold force, the second leg configured to remain in fixed position, thereby tensioning the torsion spring and retaining the drive member in fixed position, in response to longitudinal movement of the first leg when the force acting on the drive member is equal to or exceeds the threshold force.