There are many special achievements in "Lake Servant," and "Wipe the Windows Clean" is one of them. To unlock this achievement, go to the "Assist with Bathing" level, wait for Alexandra to enter the bath, interact with the window, and click on the six glass panes to complete it.
How to Unlock the "Wipe the Windows Clean" Achievement in Rusty Lake: Lake Servant
Cleaning the Windows
Wipe the Windows Clean
In the "Assist with Bathing" level, after Alexandra enters the bath, interact with the window and click on the six glass panes.
Related Guide: How to Unlock the "What You See Is What You Get" Achievement in Lake Servant