In the fanfiction, it might be that Anko was training near a body of water and got caught in a strong undercurrent. Naruto, being a strong swimmer (maybe from his time training in various terrains), could jump in and pull her out. This would also be a chance for some character development, like Anko realizing Naruto's growth and Naruto showing his selfless nature.
Naruto could save Anko from a rogue ninja who infiltrated the training grounds. He'd use his ninja skills and his determination to keep Anko safe.
Perhaps Anko was poisoned during a training exercise involving dangerous plants or substances. Naruto, with his knowledge of herbs (maybe from his time with Tsunade), could find an antidote and save her. This would show his resourcefulness and how much he has grown as a ninja. He wouldn't just rely on his combat abilities but also on his other skills.
Chapter 340, "Seclusion, the Growing Yu Generation, Family Banquet, Rapid Development (Part 4)", is the clearest early answer because it turns Han Yue's situation into a concrete plot event. The chapter turns that into something concrete by moving from Xia Hong made up his mind and withdrew his gaze, looking through the... to Xia Hong raised the cup and drank it all in one go, his cheeks....
Chapter 89, "Brother He, how can you be so unreasonable too?!", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event. The chapter gives readers a real answer by opening on Director Sun took a step back, "What's the rush?
Chapter 316, "Blood Jade Fox and Mischief, Xia City in Turmoil, Migration Begins", is the clearest early answer because it pushes Wolf King into a new phase or setting. The setup is This breathing sound is just like what we heard at the first silver..., but the pressure keeps building through Is that Beast King following us?.
Chapter 300, "Relentless Pursuit, the Beast Tide Breaks the Wall", is the clearest early answer because it turns Yuan Cheng's situation into a concrete plot event. The chapter turns that into something concrete by moving from Second Year of Great Xia, July 4th Bang... to He should have gone to inspect other places; the main zone barrier is....
Chapter 298, "Hou Jing Surrenders, White Abyss Falls, Zhaoyang Changes Its Banner (Part 4)", is the clearest early answer because it turns Chen Yingba's situation into a concrete plot event. A useful checkpoint is the way the scene starts with I am Wu Ningyuan, I am willing to surrender, please show mercy." Chen... and follows through with Walking along the northeastern snow field of White Abyss, after more....
Chapter 257, "Did Jiang Li Get in Through the Back Door?", is the clearest early answer because it turns Flash Change's situation into a concrete plot event. A useful checkpoint is the way the scene starts with This nation seemed to have a particular love for bright colors.
Chapter 329, "Refining the Jade Dew Stone, Cold Element Festival Eve (2)", is the clearest early answer because it turns Small Wooden Table's situation into a concrete plot event. The chapter gives readers a real answer by opening on Li Xuanling's talent is even stronger than her father, Li Tianhua. and ending on 1000 points of silver amounts to 5000 pounds of silver..
Chapter 343, "Five Rounds of Bone Tempering, One Thousand Bristles Bone Burning in the Visible Yang Realm", is the clearest early answer because Star finally turns buildup into a real advancement. The chapter gives readers a real answer by opening on Hong Ye and the Zhao family members happened to be walking below the... and ending on Thus, he didn't rush the breakthrough but boldly attempted a second....
Chapter 340, "Seclusion, Growing Yu Generation, Family Banquet, Rapid Development (Part 5)", is the clearest early answer because it turns Xia Chuan's situation into a concrete plot event. The chapter gives readers a real answer by opening on I haven't paid attention to the camp's situation for a whole year. and ending on Over the past year, Xu Ning has not rushed things and has slowly....
Chapter 315, "The Strange Cold Apple Tree and the Seized Silver Mine (3)", is the clearest early answer because it turns Long Mountain's situation into a concrete plot event. It opens with Thank you, Leader, for the Spirit Pill. and closes on This is almost unquestionable; otherwise, where did so many Cold.... The key payoff is that it turns Long Mountain's growth into a concrete upgrade step and sets up the next payoff in the power growth storyline linked to Li Xuanling.