If you let someone in on something that is a secret from most people, you allow them to know about it.
I’m going to let you in on a little secret...
PHRASAL VERB: V n P P n
If you let someone in on something that is a secret from most people, you allow them to know about it.
I’m going to let you in on a little secret...
PHRASAL VERB: V n P P n
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012