Return a function within another function scope?

I know this question may sound a bit weird, though please bear with me as I try to explain.

Also, I know people will try to suggest that I use .RenderStepped:Wait(), though I looked at the wiki article on RBXScriptConnections (Wiki Link) and I could not find any documentation on such function. I even tried it myself and it didn't appear to work.

What I was initially attempting to do here is create my own wait function that would wait for a RenderStepped period of time. I knew in order to do this I'd need to somehow embed a RenderStepped function inside of my main function and return the main function after a certain period of time (which the RenderStepped thing would track). It would look something like this:

function waitF(sec)
    local beg = tick()
    local f
    f = game:GetService("RunService").RenderStepped:connect(function(step)
        if tick() - beg > sec then
            --initiate the returning of the main scope somehow
             f:Disconnect()
        end
    end)
     return --return somehow
end

Though I don't know how I'd go about initiating the return. I would have to somehow yield the return part somehow and disconnect the yielding when the ffunction tells it to.