The most common and most likely answer to this crossword clue is the 9 letter word MANNEQUIN
I've seen this crossword clue in Independent
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More clues leading to the result MANNEQUIN
- Married woman, one of five, becomes model
- Noise of crazy pub still poses challenge
- Bloke posed by area of Tyne, one in five being a model
- Model that’s still on display
- Model male, born one of five
- Dummy, male with woman, one of five
- Chap, born one of large family, is a dummy
- Name of horse briefly sat on by male model
Buddy explains!

The straight part
We know that "still poses challenge" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case still poses challenge = mannequin.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 MANNEQUIN mean?
MANNEQUIN noun- A dummy, or life-size model of the human body, used for the fitting or displaying of clothes
- A jointed model of the human body used by artists, especially to demonstrate the arrangement of drapery
- An anatomical model of the human body for use in teaching of e.g. CPR
- A person who models clothes