The most common and most likely answer to this crossword clue is the 9 letter word GALVANISE
I've seen this crossword clue in Financial Times
G
A
L
V
A
N
I
S
E
More clues leading to the result GALVANISE
- Stimulate a Svengali into action
- Stir leading group on island beset by strong wind
- Shock where vehicle is caught in strong wind
- Excite young female with very sweet element in drink
- Illegal van? I secure clamping plate
- Jolt is occurring at back of vehicle in high wind
- What’s stashed in illegal van is expected to produce a shock
- Jolt as vehicle is caught in high wind
Buddy explains!

The straight part
We know that "Stir" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case stir = galvanise.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 GALVANISE mean?
GALVANISE verb- To coat with a thin layer of metal by electrochemical means.
- To coat with rust-resistant zinc.
- To shock or stimulate into sudden activity, as if by electric shock.
- To electrify.
- To switch sides between Union and Confederate in the American Civil War.