What is definition for trope?

It's a technical term in writing and the arts used to describe a word or phrase or convention that conveys a whole set of meanings. It could be a metaphor or an image or a sound, but it sets up reader (viewer, listener) with a whole background for the actual piece of work.

Like a riff in music (the start of Hotel California for example, or Gilbert and Sullivan's The Mikado) set a scene, even before one hears the "story". Or a few words in the various genres of writing (gothic, SF, Romance, thriller, Noir, etc.) you get the mood before you even get into the story.

Some tropes have become clichés

you might be able to find that online