It’s 1975’s 'L'infermiera', or 'The Sensuous Nurse', or 'Secrets of the Sensuous Nurse'... somewhat appropriately, as the title gets longer it also gets ruder.
After his wealthy Uncle Leonida suffers a stroke while banging the local gravedigger's wife, Benito Varotto comes up with a plan to finish him off and thus inherit the family's winery, which he can then sell for a tidy profit to cold-hearted American businessman Mr Kitch (Jack Palance, who appears to have taken acting lessons from a particularly grim piece of wood). He calls on his old friend and occasional bedmate Anna, a part time nurse and full time Ursula Andress, to be his uncle's private nurse.
His plan is that her hot, seductive Ursulaness will overexcite the lecherous old bastard, and thus finish the job the gravedigger's wife started and pack him off to 70s Italian Sexpolitation Heaven (a place I imagine to look a lot like an eternal Benny Hill sketch, only with Yakety Sax being played on a harp or something). Ursula being Ursula she's totally up for it, but, over time, she comes to like the feisty old fornicator, and falls prey to his well-aged charms.
But not before she's seduced his 18 year old grand-nephew, apparently more to keep in practice than for any solid reason. Having a virgin around put her off her game, I think, like a vampire who struggles to drain a maiden's blood knowing that there's a crucifx and some holy water in the next room.
But in the end Uncle Leonida is the only man for her. In due course he and Ursula are married, Benito's evil plan is revealed and Leonida kicks all his worthless relatives out of his house... except for his grand-nephew, who wasn't in on the plan. Apparently the whole "he-had-sex-with-my-new-wife" thing isn't a problem for any of them. Perhaps this happened a lot in Italy in the 70s.
Then Leonida and Ursula head off for their honeymoon where, naturally, he drops dead while enjoying his marital entitlements. This leaves Ursula as the sole beneficiary of his estate. So the original plan worked, just for Ursula rather than Benito.
At the end of the film, only one question remains: what the hell? There’s no good reason why 'L'infermiera' should be so famous. Sure, it has a naked Ursula Andress, but Ursula got her nude on in pretty much all of her movies, so that’s hardly a unique selling point. The comedy is laboured, the dialogue is trite, and there are no grand scenes or moments of action. There’s just a lot of naked Ursula.
So maybe that’s it. The movie is famous because it didn’t have anything in it that was going to distract the viewer from the many scenes of Ursula taking her clothes off and frolicking. It’s the purest ever distillation of everything an Ursula Andress movie should be.