The phrase 'in a final effort' is correct and usable in written English.
You can use it to indicate a last attempt had been made to do something. For example, "In a final effort, she submitted her essay a day before the deadline."
"This is wrong," Perkins says he argued in a final effort to derail the vote.
In a final effort the French forces checked the Prussians on September 20 , 1792 at Valmy.
In a final effort, I made an impromptu trip to Los Angeles.
That is partly because, in a final effort to keep out the opposition, the government has changed the voting system.
By the fourth quarter, the Garden sound-system has kicked into decibilic gear in a final effort to raise the dead: DEE-fense!
Last weekend, the family traveled to New York, the parents dragging their reluctant children through a Manhattan street fair in a final effort to spread the word.
The school board in the long-troubled district in Roosevelt, N.Y., made a final effort today to stay in office, defending its record at a hearing presided over by the state official seeking its removal, Education Commissioner Richard P. Mills.
In 1946, he made a final effort at a job in baseball, contacting new Yankees boss MacPhail, but was sent a rejection letter.
Celia W. Dugger (NYT) CAMBODIA: KHMER ROUGE TALKS -- United Nations and Cambodian officials began meetings in Phnom Penh in what they said was a final effort to agree on a formula for a tribunal to try former leaders of the Khmer Rouge.
Richard Hannon's colt locked horns with Dick Whittington in the closing stages but could not respond as the son of Rip Van Winkle found a final effort in the last strides.
President Obama is due back in Washington early Thursday for a final effort to negotiate a deal with Congress to bridge a series of tax increases and government spending cuts set to begin next week, the so-called fiscal cliff many economists worry could push the nation's economy into recession if it takes effect.
