The most common and most likely answer to this crossword clue is the 8 letter word BACKLESS
I've seen this crossword clue in Financial Times
B
A
C
K
L
E
S
S
More clues leading to the result BACKLESS
Buddy explains!

The straight part
We know that "As may be a dres?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case as may be a dres? = backless.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.
What does BACKLESS mean?
BACKLESS adjective- Having no back, said of things that typically have backs, such as chairs or dresses
- (of a person) having an uncovered back, having a back that shows skin