The phrase "a credible one" is correct and usable in written English.
It can be used when referring to something that is believable or trustworthy, often in the context of sources, claims, or arguments.
Example: "The report provided a credible one that supported the findings of the research."
Alternatives: "a reliable one" or "a trustworthy one."
Our process was a credible one, and the values were supported.
Prompted by Britain, the allies have done much this week to make the threat of force a credible one.
"The senior general repeated several times that they are committed to make the election a credible one".
There were no powerful shareholders to constrain the managers, and the threat of a takeover was not a credible one, since the government kept a golden share.
William German, executive editor of The Chronicle, said, "We have reason to feel his explanation is not a credible one," but he declined to be more specific.
Some experts on corporate governance have suggested that Romney's distinction between management and ownership is a credible one; others have queried it.
The EU needs a commission, and a strong and credible one, because now more than ever it needs some serious soul-searching about its capacity to deal with its own problems, and to embrace or otherwise help its poorer neighbours.
Such an outcome, however, would very probably allow him to put a strong spin on the outcome — and a credible enough one, since if Mr. Romney loses Michigan, his native state, it is hard to know where he might win elsewhere in the Midwest.
What's most powerful about the Mars books as political novels is that they envision a credible utopia, one that doesn't — unlike, say, Skinner's "Walden Two" — rely on a revision of human nature.
"Developing an interim authority has to be done by a process which is internally and externally credible", one official admitted.
It takes special historical circumstances for them to become killers: the removal of a ruling class without its replacement by a credible new one.
