'just one left' is correct and usable in written English.
You can use it when referring to something that was previously present in greater quantity, but now only one remains. For example, "I had three apples, but now I have just one left."
We're almost at the end of Nobel season, there's just one left, the prize for economics, which is announced on Monday morning.
That goes down to 32, right, then 16, then 8, then 4, then 2, until there's just one left.
Each goal was reached and ticked off until there was just one left; the most important and the most challenging.
Although there were once 10 major Armenian-language daily newspapers in the United States, there is just one left, published in California.
"At the end of the 19th century there were three bullrings in Barcelona, now there is just one left... but mostly for people who come in tourist buses from the Costa Brava," said Manuel Cases, of Spain's Animal Rights Defence Association.
Figure6b shows the time scale when just one left spin in (m,k -firm pattern for task τ3 is considered.
Without Cook, the Mets have just one left-handed reliever, John Franco; the Astros sent up two left-handed pinch-hitters, Orlando Merced and Daryle Ward to face White.
The only one left is just the boss and a few assistants.
But Oklahoma City's Serge Ibaka fouled Curry on a three-point attempt with just one second left on the shot clock and Curry made all three free throws.
With just one clinic left in Kentucky, and few left in surrounding states, the work of organizations like KHJN is becoming more expensive and logistically challenging.
Krista Meaglia assisted her sister, Britni, on a match-tying goal with just one second left in regulation.
