Acqua e sapone (1983)

An Italian-born actress-turned-stage-mother brings her daughter Sandy to Rome for three months' work as a supermodel. Sandy, who's between "soap and water" and womanhood, needs a tutor. Mom wants scholarly Father Spinelli, but when she calls his school, she reaches Rolando, a janitor who longs to teach. He's broke, so robed as a priest, he shows up to take the job. He's a terrific teacher, but Sandy soon realizes he's not Spinelli and will keep quiet only if he'll take her out under the guise of study. When Mom meets the real Spinelli and sacks the child-like Rolando, Sandy sulks; then she figures out how to act on her feelings for Rolando and her emerging maturity.