The ornamental design for a safetydevice for ladder, as shown and described.
1. Safety device for ladder
1.1 : Perspective
1.2 : Front
1.3 : Back
1.4 : Left
1.5 : Right
1.6 : Top
1.7 : Bottom
1.8 : Folded
This design is a new, original and ornamental design for a safety device for ladder, and reference is made to the accompanying reproductions forming a part thereof; we claim the ornamental design for a safety device for ladder as shown and described.