Even Houdini would get the shakes trying to wiggle out of this bind
Yes, I'm Very Sorry
Assuming he had some sexual relationship with Lewinsky, Clinton could admit it, ask forgiveness and say he lied to protect her and shield Hillary and Chelsea from public embarrassment.
People are forgiving. They might understand. Having sex is not a crime, and the perjury issue arising from his Paula Jones deposition might recede if he gave a full confession. There would be little left for Starr to prove, and Congress would have trouble investigating or impeaching him if a benevolent public were already fully informed.
He'd have to admit everything, and the public may not be that forgiving once hit with all the bawdy details.
Yes, But I Didn't Inhale
He could admit that he and Lewinsky engaged in some of the intimacies (such as "touching of breasts or buttocks") that were listed in the broad definition of sexual activities submitted to him in the Jones deposition. But he would deny that he had full-fledged intercourse or that he tried to get Lewinsky to commit perjury.
This explanation might mitigate the sense that he lied outright when he denied having a sexual relationship. And Monica has indicated that they did in fact stop short of full-fledged intercourse. If he offered a contrite apology, the public might believe him and forgive him.
He could be peppered with graphic questions when he testifies ("Exactly where did she touch you, sir?"), he'd still be exposed to a perjury rap, and he would gain little by producing a hair-splitting discussion of what really constitutes sex. And what if he had oral sex? Can he admit to that?
No, But It Was Complex
He could admit that he indeed had a "complex" and "close" relationship with Lewinsky, concede it was "inappropriate" but insist that it wasn't sexual. He could try to deflect questions about the personal details of his encounters, calling such queries indecent and inappropriate, and say it was up to Congress to decide his fate.
It would help explain the gifts, the visits and perhaps even the job hunt, and it might convince some people that Monica was fantasizing. A weary public might appreciate his reticence.
At the very least, trying to explain all the complexities is embarrassing, and it doesn't help him if there's independent evidence that he had sex. And if he skirted too many questions, Starr might serve another subpoena.
No, No, Never
He could continue to insist that he did not have sex with that woman.
Remember, it might actually be true, and people might believe him. It could come down to his word against hers. If there is no proof of sex, then there is no proof of perjury.
Monica's detailed testimony could be very incriminating; there may be corroborating witnesses; and don't forget that dress. Starr's report could be damning and the congressional hearings brutal.