It crops up in middling time, this thought (6)

I believe the answer is:

notion

I'm a little stuck... Click here to teach me more about this clue!

'this thought' is the definition.
(notion is a kind of thought)

I don't understand how the rest of the clue works.

(Other definitions for notion that I've seen before include "Vague or fanciful idea" , "Idea or fancy" , "Whim or fancy" , "Vague understanding" , "Vague impression" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.