The most common and most likely answer to this crossword clue is the 8 letter word MODESTLY
I've seen this crossword clue in Financial Times
M
O
D
E
S
T
L
Y
More clues leading to the result MODESTLY
- Cover girl, say, crossing street, unknown character in low-key fashion
- Youth subculture style evolved without ostentation
- A little bit more, half imaginatively styled
- Fashion model entertained by Stallone, with discretion
- Above all maintaining editor’s sent up in an unpretentious way
- Doctor styled scruffily in humble fashion
- Melody dances across street without pretension
- Vogue stumped by lady’s dressing without extravagance
- Member of teenage group changing style with diffidence
- Decently, mostly - half-dead inside
Buddy explains!

The straight part
We know that "without ostentation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case without ostentation = modestly.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 MODESTLY mean?
MODESTLY adverb- In a modest manner.