The most common and most likely answer to this crossword clue is the 9 letter word PINAFORES
I've seen this crossword clue in The Guardian
P
I
N
A
F
O
R
E
S
Buddy explains!
The straight part
We know that "Dresses" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dresses = pinafores.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 PINAFORES mean?
PINAFORES noun- A sleeveless dress, often similar to an apron, generally worn over other clothes. Most often worn by young girls as an overdress.