The most common and most likely answer to this crossword clue is the 6 letter word DIRNDL
D
I
R
N
D
L
Buddy explains!

The straight part
We know that "skirt" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case skirt = dirndl.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 DIRNDL mean?
DIRNDL noun- A traditional Alpine women's dress having a tight bodice and full skirt