Few TV movies have earned their "parental guidance" disclaimers as royally as "Off the Minnesota Strip," the ABC movie at 9 tonight on Channel 7. But the film, while dealing with the sensational subject of teen-age prostitution, is uncommonly grim and investigative and intelligently done.

It is not a piece of gross exploitation nor an alarmist shriek about moral decay. Yet it is, in a thoughtful and unflinching way, a shocker. Writer David Chase obviously got his idea from newspaper stories about teen-age Midwestern girls being lured to New York and their lives as nymphet hookers. Rather than play peekaboo with tawdry urban subcultures in the usual TV movie way, Chase looks at a fictional young girl's problems of readjustment upon returning home in disgrace to Mom, Pop and apple pie.

It's an American nightmare that comes across as chillingly plausible and timely. But unfortunately for Chase and co-producter Meta Rosenberg ("The Rockford Files"), "Minnesota" drew the booby prize in the chancy game of network scheduling. It will air tonight opposite the TV premiere on NBC of 1979's exhilarating populist smash "Breaking Away," and so will not have access to the audience it deserves.

Among the distinctions of the film are Lamont Johnson's direction, non-hysterical to a fault and movingly deliberate, and Mare Winningham's complex and incisive performance as Micki, a girl from the right side of the tracks who is into prostitution before her teeth are out of braces.

Winningham played the agreeably sassy and independent daughter of a dying wheat farmer in "Amber Waves" on ABC earlier this season. Here she proves capable of a 360-degree spin as the child who becomes a woman too soon and returns home hardened and cynical about the world and the men in it.

But the film isn't just another medley of scare tactics about the evils of the big city. Micki did not leave home unscarred in the first place, and the revelation of an incident that contributed to her debasement is a devastating jolt Chase saves for the last half hour -- not, however, as a deus ex machina, since the film is a little too sophisticated to let any of the characters completely off the hook.

Hal Holbrook and Michael Learned play the parents again bringing some fresh variations to characters that might have played as stick figures out of pop sociology. Chase has an ear not only for small talk among teen-age girls ("New York's a fashion center just like Paris -- that's what Cher said on 'Merv Griffin,'" notes one of Micki's high-school friends) but also for the sometimes revealing triviality of dinner-table conferences.

Holbrook is especially and perhaps surprisingly good as the emasculated father whose prescriptions for recovery are pretty much limited to fried-egg sandwiches and choruses of "My Way." When he breaks down in blubbery confession late in the film, the effect is pretty stunning. Learned gives the mother a ferocity that is definitely to be reckoned with.

Additionally notable are Heather McAdams as Micki's younger sister ("You're just like on 'Kojak' -- you're a whore"), Ben Marley as a sexually inexperienced young man at John F. Kennedy High ("Would you go to to bed with me for $30?") and Leon Isaac Kennedy as the cunning, satin-voiced pimp.

Yes, the pimp is black and the girl is white, but Chase does try to make it clear early in the film that in the sexual "supermarket" flourishing in American cities, America truly is a melting pot in which there is no steadfast correlation between race and the role being played.

What Chase and Johnson have done is to raid the headlines in the time -tested TV movie way, but they have managed to make a film that deals with exploitation rather than one that embodies it -- a very rare trick, and one that is commercially more risky than the alternative.

"Minnesota Strip" leads to intricate, pertinent questions about sexual behavior, hypocrisy and debasement, and at the same time maintains a natural, pervasive sense of social context. These are the kinds of qualities missing from the CBS movie on the aberrant behavior of Jim Jones and his followers: that picture was merely a calculated and low-minded recitation of events with no purpose in the world other than securing an audience for advertisers.

With "Off the Minnesota Strip," one is reminded of how tellingly television can deal with difficult, even threateingly intimate subject matter. its $99(Words ILLEGIBLE) may bring to mind the lurid movie melodrama "Hardcore,) but in attention to detail, appreciation of nuance and integrity of intent, "Minnesota Strip" is about 1,000 times better.