Memorial plate on a wall (6)

I believe the answer is:

plaque

(Other definitions for plaque that I've seen before include "Film on tooth" , "film in bad taste?" , "Film on teeth that encourages caries" , "Brass memorial tablet" , "Trophy" .)

I've seen this clue in The Guardian.

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.