The phrase "a sort of third" is correct and usable in written English.
It can be used to describe something that is not quite a full third but has characteristics of one, often in a comparative context.
Example: "In this competition, she was a sort of third, not quite a finalist but still deserving recognition for her efforts."
Alternatives: "kind of a third" or "somewhat of a third".
Ms. Chlumsky turns up as a sort of third point in a semi-romantic triangle.
The issue of the conditions under which iPads and other personal devices are made is a sort of third rail of the digital industry.
So Bilgi became a sort of third track, as "the only education-led artistic resource where the ambition was to engage artists," Ms. Aksoy said.
The 'Backs are a sort of third world expansion club lucky enough to discover two great natural resources, Curt Schilling and Randy Johnson.
Whether the series of campus demonstrations in recent years will escalate into a sort of third wave of student movement, on the order of antiwar or divestment, remains a question.
They may not have been earth-shattering but Obama's successes – including the fact of his election – reflected a sort of third reconstruction, the antithesis of which is breathing heavily on the backs of people's necks.
So perhaps Crouch's concept of "the guide" offers us a sort-of third way, one in which theatre makers don't have to make a brutal and sometimes impossible choice between pandering and patronising.
It's been called bad because it appears to be a truncated, unauthorized version of the play-a sort of seventeenth-century bootleg.
"The recurring dream is I'm seeing what's happened from a sort of third-person standpoint.
Throughout southern Africa, cable theft is ubiquitous, a sort of third-world analog to first-world thefts of car radios.
In a sort of third-person monologue of impressions, vignettes, and diaristic reflections, he comes off as neither heroic nor craven, though he exhibits both traits on occasion.
