After looking again today, I see what I would say is definitely the right shot here - because it's effective, and mega-simple to execute...last night I didn't notice that there was room for the cueball to pass through, but it looks like there is room - if not, then of course the shot isn't available...
The shot is to just shoot the cueball straight across between the two dark-striped balls, then striking the left side of the 3ball - at this point you have two choices - both good in their own way...you can shoot very soft and come off the long rail leaving him snookered behind the 1ball - or, you can shoot it a little harder, come off the long rail and knock his 1ball away from his side....both choices have an extra benefit that come with them....shooting the harder speed, you get to bank the 3 over to your side at the same time....and if choosing to shoot it at the soft/snookering speed, you will be able at the same time, to naturally, shoot it in such a way so that you have the 3ball tie up his 4ball.
- Ghost
PS, And for those on here learning....even if this shot is not available here (or because of how much of the 3 can be seen, maybe only one of the versions is available here)...it's a shot that comes up countless times in the early stages of the game, and it's good for you to see the shot, and know the two different ways to shoot it, and the benefits from each.