Sakura would probably be shocked at first, but then she'd get angry. She'd immediately start to struggle and try to free herself. She might call out for help if she thinks there are allies nearby.
Well, it might be part of a plot where the clone is trying to capture Sakura for some reason. Maybe Madara (or whoever controls the clone) wants information from her. Sakura, on the other hand, is not one to be easily intimidated. She might start by trying to talk her way out of the situation, but if that fails, she'll surely put up a good physical fight. She could use her chakra - enhanced punches to try and shatter the clone.
I'm not sure specifically as there could be various interpretations. It might be about Madara's Limbo clones interacting with Sakura in some sort of fictional scenario created by the fanfic writer.
Obviously, Madara (or his Limbo clones) and Sakura are the main characters based on the title.
Naruto would be extremely enraged. He would vow to rescue Sakura no matter what. He would immediately start gathering his friends and form a rescue team. Sasuke, on the other hand, might initially seem more reserved but would also be determined to get Sakura back. He would use his Sharingan skills to track Madara.
She might be surprised at first. After all, Naruto isn't known for his singing usually. But then she could be touched if she realizes the song is for her and about their relationship, whether it's friendship or something more.
Sakura would probably be horrified. She knows Orochimaru's reputation for being cruel and power - hungry. She would immediately reject any offer from him and get ready to fight if necessary. After all, she has grown into a strong kunoichi and won't be easily intimidated.
Sakura might initially be terrified. She would probably try to fight back using her combat skills and medical ninjutsu to defend herself. Since she is a strong - willed character, she won't go down without a fight.
Aqua, if she were involved, would be determined to save Kairi. She has a strong sense of justice and protecting the innocent. She would likely use her magic to try and track Xehanort and Kairi. Donald and Goofy would be loyal to Sora and follow him into the fray, but also try to keep Sora from making hasty decisions. They would offer their support in combat and also try to think of practical ways to free Kairi, like finding Xehanort's weaknesses.
She would be heartbroken. Sakura has known Naruto for a long time, and his death would shatter her world. She may become more withdrawn and serious. In the long run, she could use her pain as motivation to become stronger. Maybe she would train harder than ever before to make sure that no one else has to suffer the way Naruto did. She might also start to see Naruto in a different light, realizing all the things she took for granted when he was alive.
She would also be deeply emotional. Sakura has deep feelings for Naruto, even if they were not always fully realized or expressed. His sacrifice would make her confront these feelings head - on. She could be seen crying often, visiting Naruto's memorial frequently, and having long internal monologues about their relationship and what his sacrifice means to her.