Since the ball can not be nudged or it pockets, and you do not want to make it and scratch then I have a couple of ideas.
1. very high powered and way beyond my skills, but to jump the cue ball into back of pocket and have it rebound back and knock the object ball out without scratching! Pretty far fetched!
2. make the ob and draw the cue ball to the spot, whereas when the ob is spotted it either freezes the ob to the cb or the cb is very close to the ob making it near impossible to bank. I like this option much better than 1.
3. If it is a drop pocket hopefully your other four balls are in that pocket, if not put them all in there, and blast the shot, the ob ball may jump out! lol !!!
thanks, for the thread it is a head scratcher! Whitey