LOS ANGELES, Oct. 28 – The defense wants John Lennon of the Beatles to testify in the Sharon Tate murder trial on whether one of the group’s song could have inspired Charles Manson to violence. But, in London, a spokesman for the Beatles said today that is “like summoning Shakespeare to explain Macbeth.”

What’s more, said the spokesman, the song in question “Helter Skelter” — was written not by Lennon but by Paul McCartney, another Beatle.

“We want John Lennon to testify,” a defense source said in an interview Tuesday. “We feel he may want to explain the lyrics.”

The state has asserted that Manson ordered his followers to kill Miss Tate and six others in August of 1969, aiming to trigger a race war which he felt was predicted in “Helter Skelter.”

The source, who asked not to be identified, said the defense has been trying for months to subpoena Lennon, who is believed to be still in the Los Angeles area, but “there is an unbelievable wall surrounding him.”

However, the Beatles spokesman said Lennon has been in London since the end of August after a six-month vacation in California.

As for whether “Helter Skelter” contains hidden appeals for violence, the spokesman said this is “ridiculous — a fantasy.”

The defense case is scheduled to open next week — the 21st week of the trial. The source said it would last about a month. Manson, 35, and three young women followers are charged with murder-conspiracy in the slayings.

Other entertainment personalities have been subpoenaed, the source said.

Among those scheduled to take the stand are Mama Cass Elliot and John Phillips, both former members of the Mamas and the Papas singing group.

Both are said to have known Manson in 1968 when he tried for a career as a musician and socialized with recording personalities.

“All of these people are extremely reluctant to testify,” said the source, “but they are under subpoena.”

He said the women defendants in the case are not expected to take the witness stand.

Manson is scheduled to be the last witness for the defense.

“He is naturally the last witness,” said the source. “You put the children on before you put the father on. He is the natural conclusion. We’d like this testimony to be vivid in the jury’s mind.”

Much of it is expected to be Manson’s version of the philosophy he preached to members of his hippie-type “family.”

A four-pronged defense is planned, the source said. It will seek to:

— Cast doubt concerning the identity of the killers. “We are going to try to prove that other people committed the offenses.”

— Discredit the testimony of Linda Kasabian, the state’s star witness, by calling character witnesses to say she was known to lie. Among them will be a social worker who says Mrs. Kasabian told her she was out of California when the murders occurred.

— Rebut the prosecution’s case by calling to the stand every key person named in testimony. Several prosecution witnesses may be recalled. Also on call are persons named as having provided knives to other implements allegedly used in the crimes.

— Explore Manson’s philosophy by putting family members on the stand — “There are probably about 10 members still in this area. They will really elucidate the philosophy of Manson and show his benevolent side. They will show him as a great non leader who sometimes kissed people’s feet and usually was the last to eat at dinner time.”

By LINDA DEUTSCH