The most common and most likely answer to this crossword clue is the 8 plus 5 letter word SANDWICH BOARD
I've seen this crossword clue in The Times
S
A
N
D
W
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C
H
B
O
A
R
D
More clues leading to the result SANDWICH BOARD
- Ads for carrier go on to support submarine?
- Kent town fed up, we hear, producing old-fashioned advertising
- Lunchtime snack to get on publicity platform
- Advertisement from Kentish golf course committee?
- Kent town with management team providing promotional material
- Put squeeze on directors for advertising material
- Advertising that’s sometimes covered by film directors
- Advertiser offering snack and regular meals?
Buddy explains!
The straight part
We know that "Advertisement" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case advertisement = sandwich board.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.