Identify this weed please.

[Analog6 (Odille)]

I'd try Roundup. Get a wand type applicator so you can apply it just to the weed. However, as mentioned it may be resistant.

Also. as it is a legume, it may be coming from birds droppings in your garden, so the problem may just keep recurring.

At least it's green!

[Ian Robinson]

You could always try napalming the stuff , one of those little butane bottle fueled torches would do the trick.