Button clicked tool cloned into backpack?

Assuming you already have a button and gui put the following into a local script:

local button = script.Parent
local weapon = game.Lighting["WEAPON NAME HERE"]
local plr = game.Players.LocalPlayer

button.MouseButton1Down:connect(function()
    local cw = weapon:Clone
    cw.Parent = plr.BackPack
end)

Your code should look something like this I'm not on my computer so there is probably some sort of error but you should be able to figure that out good luck on your game.