The most common and most likely answer to this crossword clue is the 5 plus 4 letter word DRESS DOWN
I've seen this crossword clue in Independent
D
R
E
S
S
D
O
W
N
More clues leading to the result DRESS DOWN
- Tear off a strip for inappropriate state of attire
- Slob around, frock round ankles?
- Carpet to decorate with feathers
- Change blue carpet
- Carpet to appear scruffier
- Trim blue carpet
- Appear casual in gown with soft texture
- How 7 may be exposed — producing reprimand?
- Wear casual clothes to lecture
- Put casual clothes on carpet
Buddy explains!

The straight part
We know that "Put casual clothes on/carpet" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case put casual clothes on/carpet = dress down.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.