The most common and most likely answer to this crossword clue is the 8 letter word PLEBEIAN
I've seen this crossword clue in Financial Times
P
L
E
B
E
I
A
N
More clues leading to the result PLEBEIAN
- Common person that is to be back in scheme
- European in biplane flying low
- Commoner, English, in biplane flying
- Common to see biplane flying round east?
- Design surrounding emblem is oddly vulgar
- Enable pi to be computed but not refined
- Unrefined Ecstasy taken by quiet homosexual the Sun outed
- Labourer‘s request, note, about live current
- Be in place with English man of the people
- Vulgar ‘bleep’ in a broadcast
Buddy explains!

The straight part
We know that "not refined" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not refined = plebeian.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 PLEBEIAN mean?
PLEBEIAN noun- A member of the plebs, the common citizens of ancient Rome.
- A commoner, particularly a low, vulgar person.
- Of or concerning the plebs, the common citizens of ancient Rome.
- Of or concerning the common people.
- Common, particularly vulgar, crude, coarse, uncultured.