Crossword Genius

Summarily dismissed with this noise, lean out in panic (4,2,4,3)

Ross

I believe the answer is:

flea in ones ear

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?

I've seen this clue in The Guardian.
Want a hint initially instead of a full solution? Install my app