Possible Clues:

• Non-native speaker's subj
• Night sch. offering
• Immigrant's class, in brief
• Class for some immigrants, for short
• Subj. for many an au pair
• Course for some new U.S. residents
• Class for U.S. immigrants
• Course concerned with idioms: Abbr
• U.S. newcomer's course, perhaps
• New U.S. citizen's course