Repair grooves in plaster

[Bigfoot]

I need to repair a wall, the wall is an apartment partition and consists of double plasterboard on steel studs and insulation.
Someone has cut a groove through both layers of plasterboard (and then glued wainscoting).

Can the groove be repaired with plaster compound or similar without having to open the wall more and fiddle with some form of noggins behind?

 

[nevinator]

If it's not more than what's visible in the picture, I would have bought a tube of grovspackel and filled it in a few rounds with drying in between https://www.xlbygg.se/kopparberg/so...packel-fix-fog/grovspackel-beckers-0-4l-38764
If the surface needs to be fine, I would have finished with a finer spackel.
But there will surely be wiser advice from more experienced people.

 

[Daniel 109]

If you estimate the gap at 16mm for the railing tube per linear meter before it dries. Buy a bucket.

 

[JanneJanne123]

And don't forget to put a strip over it, otherwise it will quickly crack.

 

[Bigfoot]

Thanks for the answers, I'll go ahead and won't forget the remsan.