Completely lacking in intelligence (7)

I believe the answer is:

vacuous

(Other definitions for vacuous that I've seen before include "Devoid of significance or point" , "Empty; inane" , "Empty-headed" , "Hollow" , "Expressionless" .)

I've seen this clue in The Times.

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.