Help with tree stump!

Hi all, this is my very first post here, I need your gardening expertise!

We had a tree removed a couple of months ago (I nor anyone who saw it actually knew what it was) and this (photo attached) is sprouting from the stump. I know that trees can start to re-grow, would it have happened this quickly or is this a weed i'm dealing with? I've already pulled/cut it all back once so it's growing quite aggressively.. Can anyone identify this and even better advise how I can stop it growing back? It's unsightly!

Many thanks in advance,
Kate

 

Looks like a willow, not sure which one.....maybe goat willow.

 

Get some Root Out, drill several holes in the stump, fill the holes with the killer then cover the stump with some polythene, (to keep away any animals). It will take a while to work though.