The phrase "accept one thing" is correct and usable in written English.
You can use it when discussing a specific condition or aspect that is being acknowledged or agreed upon.
Example: "In our negotiations, we must accept one thing: compromise is essential for progress."
Alternatives: "acknowledge one fact" or "agree on one point".
Yet, whatever the outcome of the struggle to force him to accept electoral defeat, one thing was clear: the logic of Mr. Milosevic's hold on the people of Serbia had been shattered.
For progress in human relationships, Dr. Glasser says, people need to give up trying to control others and accept that the one thing they can control is their own behavior.
They have accepted that there is one thing that links all the questions addressed by the inquiry: why did the phone hacking take place?
"To accept their ultimatum is one thing, negotiating to save hostages is another".
Conkling, still in a tantrum over Grant's loss, told Arthur he was not to accept the nod; for one thing, Garfield was bound to lose in the fall.
"They had disagreements with me that I can accept but we had one thing in common: we loved Arsenal football club and I just wanted to share that with them".
Admiring the analysis is one thing; accepting the policy prescriptions quite another.
For one thing, despite accepting payments on their site, there was no company information, no privacy policy, no terms and conditions and no obvious means to get in touch with the people who had made it.
It is one thing to accept that the world may not have the resources and the dexterity at this moment to provide the finest of medical care to all, but that is not a reason for eliminating our search for ways of proceeding towards just that, nor a ground for refusing to provide whatever can be easily provided right now for all.
It's one thing to accept that one day these issues might be better addressed by scientists than philosophers, quite another to hand them over prematurely.
