Depends on knowledge they had on each other as Akatsuki partners. Does Kakuzu know Deidara is a doton user? If it's the case, it will be a peace of cake for him to defeat Deidara. Beside Doton domu that could counter majority of Deidara's attacks(C1, C2) besides C3 or C4 maybe, he possess raiton that would neutralise it's effects. And with his large and powerful ninjutsu attacks, he would sure kill a mid range flying Deidara at some point. Not even mentioning the fact that Deidara even has to kill him 5times to defeat him. Kakuzu has an overwhelming advantage over Deidara. His ninjutsu won't work, Stamina disadvantage, has to kill his opponent 5times, and he couldn't escape all of his attacks