The most common and most likely answer to this crossword clue is the 8 letter word UPSTROKE
I've seen this crossword clue in Financial Times
U
P
S
T
R
O
K
E
More clues leading to the result UPSTROKE
- Writer’s movement finished, author’s right significantly advanced?
- Puts out smoke? One’s lacking in p’s and q’s
- Excited by cricket action? It’s part of a sportswriter’s character
- Raise Pat in an artistic movement?
- Purest works preserving fine motion of paintbrush?
- Our son kept failing in a movement towards higher position
Buddy explains!

The straight part
We know that "motion of paintbrush" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case motion of paintbrush = upstroke.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 UPSTROKE mean?
UPSTROKE noun- The upward stroke of a pen, brush, piston, etc.