City Council President George L. Forbes, the citys' top black political leader and chief adversary of Mayor David J. Kucinich, was cleared today of public corruption charges.

Forbes, 48, had been charged with 11 counts of intimidating a police officer, bribery, theft in office and extortion in connection with an alleged carnival gambling kickback scheme.

Common Pleas Court Judge George B. Tyack, saying the state provided only circumstantial evidence, delcared Forbes not guilty on all counts.

The trial, which started July 2 and is among the first to be covered by television cameras, will continue for Forbes' police bodyguard, Curtis Watkins, who is charged with nine counts of forgery.

Forbes had also been indicted for engaging in organized crime, but that charge was ruled unconstitutional by Tyack and dropped in pretrial hearings.

Assistant County Prosecutor Donald Nugent said Tyack's ruling on the organized crime charge has been appealed. If a higher court reverses the decision, he said, "we will try these men again."

The trial was politically significant for Kucinich, who faces reelection this year. Forbes' acquittal could undercut Kucinich's claim that the City Council is corrupt. Also, Forbes is now free to back Council Majority Leader Basil M. Russo, Kucinich's top challenger in the mayor's race so far. Russo is hoping for strong support from the city's black community.

The case stemmed from a Cleveland Plain Dealer investigation of the alleged City Hall protected carnival gambling scheme. Forbes and other city officials were accused of accepting bribes for permits for carnivals where illegal gambling was said to be conducted.

The newspaper series led to the indictment of Forbes, Watkins and 16 other persons, including four present councilmen and two former legislators, on almost 500 charges. The other defendants include carnival operators and workers.

Nugent contended that the evidence proved Forbes received up to $11,000 in 1974-75 from concessions.

A key prosecution witness, Lewis H. Thompson, a former carnival president, testified that he gave Forbes $11,000 for permission to hold carnivals.

His testimony, however, was discredited when he admitted under cross-examination that he had suffered some memory loss in 1976 after a hurricane felled a building on him in Ocean City, Md.

In the Plain Dealer series, Forbes acknowledged receiving $4,000 from carnival operators, but said the money went to charity. That statement was made in a taped interview but Tyack refused the prosecution's request that the recording, made by reporter Daniel I. Biddle in January 1978, be introduced as evidence.

Instead, Biddle was required to testify from memory on the interview and, in doing so, made statements that court observers said were favorable to Forbes because Biddle stressed Forbes' comments about turning the money over to charity.

Tyack, in dismissing the charges, said, "There was no evidence that Forbes accepted money to influence his official conduct or that the money was improperly utilized."

County Prosecutor John T. Corrigan, in a bitter statement issued after Tyack's decision, said, "There is no question that it was shown and admitted by Mr. Forbes that he had received money. If that isn't theft in office, if that isn't bribery, then there's something terribly wrong with the law or the judge is wrong."

After the ruling, Forbes said, "I'm grateful to God." He refused to comment on the case because several colleagues still face trial.

One of his lawyers, James Willis, said, "I am thoroughly convinced that the charges against Forbes were both racially and politically motivated. Nothing of this nature could have proceeded without Dennis Kucinich's involvement and the imprimatur of Corrigan." CAPTION: Picture, George L. Forbes and wife Mary are interviewed after his Cleveland acquittal. AP