let fall something

let (something) fall

To accidentally or inadvertently reveal some secret or important piece of information. I can't believe your sister let news of our engagement fall in front of your parents last night! The agent, under the influence of a powerful truth serum, let fall the names of other operatives working covertly in the area.
See also: fall, let

ˌlet ˈfall something

mention something in a conversation, by accident or as if by accident: She let fall a further heavy hint.
See also: fall, let, something