Featuring a prominent and unique opening chord, the song's success provided the first inkling that The Beatles were not the one-hit wonder some had suggested when they first came to America. —A Hard Day's Night (song).
a slight suggestion or vague understanding; "he had no inkling what was about to happen"
If you have an inkling of something, you have a vague idea about it. I had no inkling of his real purpose until much later. a slight idea about something suspicion (Probably from inkle (1300-1400))