Answer: Kindergarten Cop
Penelope Ann Miller, whose credits include "Other People's Money" (1991), "Chaplin" (1992), and "The Relic" (1997), played Joyce Palmieri (aka Rachel Crisp), the ex-wife of a suspected drug dealer that Arnie is trying to nab. Arnie took on the undercover assignment of a kindergarten teacher because her son was one of the students (and besides, his partner, played by Pamela Reed, got seriously ill).