@Matthias, now I got the point, for clipping top-Cell name is mandatory otherwise tool is got confuse which cell you are selecting.
here is my code that is working fine but kindly review once, that my approach is correct or not ?
KLAYOUT = pya.Lay…
In above script the name of top-cell is hardcoded (top_cell_read.name != "xyz.gds":), but I want to find top- level cell from GDS via script then change the top-cell name.