Clothed in insufficiently formal attire (12)
I believe the answer is:
underdressed
(Other definitions for underdressed that I've seen before include "Clothed too plainly" , "Too informally clothed for the occasion" .)
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.