(archaic) Having clandestine or illicit intercourse.
1839, Michael Ryan, Prostitution in London (page 83)
[…] few respectable women will now sit at a window, looking into the public street, or gaze at passengers in any large town or city; and no one does so at present, unless an innocent inexperienced, husband-hunting, flirtish, or intriguing person.
(Can we date this quote?), Thomas Longueville, The Curious Case of Lady Purbeck
In all these negotiations, and caballings, and intriguings, the person most concerned, Frances Coke, the beauty and the heiress, was only the ball in the game.