A clash between Shanks and Akainu would be within reason, but even then I’d argue Shanks lacking enough relevance to clash with the two main antagonists on the seas (Blackbeard & Akainu), but a straight up defeat of Akainu sounds batshit crazy
The marines are the biggest and strongest faction, currently ruling the seas, a faction Oda has been building up arc after arc since chapter 2. Sakazuki as the current Fleet Admiral is the most powerful man in the New World, and when it comes to individual strength he is the only character to properly defeat a top tier, and not any top tier but Garp’s protege himself. Ever since he has lead the marines to become the strongest they’ve ever been.
This man is the only one to scar the main character, break his will and kill one of his loved ones
But Shanks will defeat him because Midd will obviously defeat Ryokugyu
