From Longman Dictionary of Contemporary Englishharp on about something British English, harp on something American English phrasal verb informalTALK TO somebodyto talk about something continuously, especially in a way that is annoying or boring My grandfather harps on about the war all the time. → harp→ See Verb table
Examples from the Corpus
harp on about • But the Tories would be unwise to harp on about Mr Kinnock's. 