THE HONOURABLE SCHOOLBOY, by John LeCarre (Knopf, $10.95). When he uncovered the mole in Tinker, Tailor, Soldier, Spy, George Smiley also revealed a mortal wound in the vitals of The Circus, the eccentric, gentlemanly but oddly effective British intelligence agency for which he worked. In the latest installment, he comes out of retirement to try to rebuild the shattered organization - and since LeCarre is the author, he has mixed results. The locale shifts from the European focus of earlier books, with much of the action taking place in Hong Kong and in Southeast Asia toward the end of American military involvement in Vietnam. The characters are vivid, the style dry and readable, the expertise in the folkways of spies and bureaucrats as impressive as always.

THE SECRET LOVERS, by Charles McCarry (Dutton, $8.95). Lovers in secret, lovers of secrecy, the title cuts both ways in its application to this intricate, sensitive story about espionage and the way it affects the private lives of its practitioners, by the author of The Tears of Autumn.

ORCHIDS FOR MOTHER, By Aaron Latham (Little Brown, $8.95). If this novel were a little better, it would be a close American counterpart to LeCarre's series on The Circus. The main characters (rather closely modeled on real CIA personalities) are vividly presented and the portrayal of the bureaucratic maneuvering that underlies the business of espionage is microscopically precise. A too-spectacular final scene and a slight excess of name-dropping are among the few drawbacks in a book that is otherwise absorbing and well-styled.