This is a container clue - one word or phrase is placed inside ('with border') another word to form the answer.
Look for a word meaning 'notice' (like an advertisement) that gets placed inside a word meaning 'garish'. The phrase 'with garish border' indicates that the garish word wraps around the notice word.
Answer: SHADOWY | AD (advertisement, 'notice') goes inside SHOWY ('garish') to form SH-AD-OWY, meaning indistinct.