If it's come from a patchbay, then it would likely have been used in balanced operation, which is Sleeve Ground, Tip Hot, and Ring Cold (unless it's the US, where Hot and Cold might be swapped). For unbalanced operation (as is with guitars), you ditch the Cold connection, and this can be connected to ground if you want.
You'll probably need to drill out the hole for the socket as the locking ones are bigger, but i'm sure you've seen that already :)