Promptly ignores rebuke without much thought (4)

I believe the answer is:

idly

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

But I can't explain it at all! Could you help me understand?

(Other definitions for idly that I've seen before include "in a way vain" , "In a lazy manner" , "How one may stand by" , "So lacking purpose" , "How one stands by?" .)

I've seen this clue in The Hindu.

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.