Painter's undercoat (6)

I believe the answer is:

primer

(Other definitions for primer that I've seen before include "Basic teaching book" , "introductory book" , "it might be used by one 7 [PAINTING]" , "School textbook" , "Reading book" .)

I've seen this clue in the Sydney Morning Herald.

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.