Well, one possibility could be that in this fanfiction, Naruto is somehow transported to the One Piece world and is banished by the World Government because they see his ninja powers as a threat. He then has to team up with the Straw Hats secretly to take on the World Government while hiding his identity.
Maybe Naruto is banished from his own ninja world and ends up in the One Piece universe. There, he might start off as an outcast but slowly gains the respect of some pirates. He could use his jutsu skills to help them in battles against other pirates or the Marines. For example, his shadow clone jutsu could be used to confuse enemies during a sea battle.
In a 'Naruto banished One Piece fanfiction', it could be that Naruto's presence in the One Piece world is seen as a disruption to the balance of power. The Marines banish him to a remote island. However, he meets a group of misfits on the island who are also against the World Government. Together, they start a revolution of sorts, using Naruto's unique abilities and the knowledge of the misfits about the One Piece world.
Chapter 545, "Kiss Me", is the clearest early answer because it turns Jiang Cheng's situation into a concrete plot event. Early on, Truth or dare, I still choose dare!" He just didn't believe it, Jiang.... By the end, I was wondering why you were so sheepish around us, I thought you had....
Chapter 779, "Unmarried but Have a Daughter?!", is the clearest early answer because it turns Chen Qijun's situation into a concrete plot event. It opens with Right, there's one more important thing," Shen Lan looked at Chen...
Chapter 807, "If You Dare, Go Complain Now", is the clearest early answer because it turns Lin Manru's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jiang Bufan had barely eaten dinner, having spent the whole day being...
Chapter 754, "Evil Can Never Defeat Justice", is the clearest early answer because it turns Miss Shu Yan's situation into a concrete plot event. The chapter turns that into something concrete by moving from After the court trial ended, everyone immediately threw a party for...
Chapter 566, "New Game Begins!", is the clearest early answer because it turns Luo Xuan's situation into a concrete plot event. The chapter turns that into something concrete by moving from How is that possible?" Luo Xuan frowned, "What's the rush?
Chapter 551, "Who is Reciting "Student Rules"?", is the clearest early answer because it turns Student Rules's situation into a concrete plot event. The chapter turns that into something concrete by moving from Other competitors were already in place, and Qi Tianyu was the last...
Chapter 770, "You're Actually Speaking Up for Her?!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. Early on, Back in Chixia Village, Jiang Li had already begun showing utter....
Chapter 737, "Shu Yan in Trouble!", is the clearest early answer because it turns Sister Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from South City Film and Television Shooting Base.
Chapter 553, "His Love Runs Deep", is the clearest early answer because it turns Team's situation into a concrete plot event. It opens with His gaze shifted to Luo Xuan's empty hands, and Ai Xiaochun's... and closes on We could use this to our advantage..
Chapter 677, "Worshiping Sister While Avoiding Them", is the clearest early answer because it turns Jiang Shixu's situation into a concrete plot event. The chapter gives readers a real answer by opening on You should learn from your sister; she's made her own fortune and is...