THE Westbrook Trio makes a one-night stand at City Hall on Wednesday. The jazz trio is comprised of vocalist Kate Westbrook, composer and pianist Mike Westbrook and hard-hitting saxophonist Chris Biscoe. Together they perform a cabaret, purported to be an evening of witty theatrical entertainment. Tickets $60 and $100 from URBTIX outlets. WILL she or won't she is the big question in the film that has set Hollywood on fire. Demi Moore stars in Indecent Proposal as the woman who receives an offer she cannot refuse from Robert Redford. Coming to cinemas later this month, the controversy centres on what happens when Redford meets married couple Moore and Woody Harrelson in Las Vegas and offers them the deal of a lifetime. A million dollars for just one night with the dewy-eyed Moore. Would you or wouldn't you? Also on the movie front Teenage Mutant Ninja Turtles III will open in cinemas next month. Starring mainland actress Vivian Wu, the set is supposed to be spectacular and the plot ''even better'' than previous versions. But the ''biggie'' this summer will be Steven Spielberg's long-awaited Jurassic Park opening on July 29. Although top billing goes to Jeff Goldblum and Laura Dern (who are reportedly an off-screen item now), they are no competition for the scary monstersthat take over the screen. THE latest in the MTV Unplugged series is a 10,000 Maniacs concert premiering on Wednesday at 2 am. It will be re-broadcast on June 13 at 8 pm. Special guest star Talking Heads' David Byrne joins Maniacs lead singer Nathalie Merchant on stage.