The most common and most likely answer to this crossword clue is the 6 letter word TROIKA
T
R
O
I
K
A
More clues leading to the result TROIKA
- Team making comeback in Nagasaki or Tokyo
- Supply kit, not primarily for a team of 3 15 15s?
- Group of three in one go-kart crashed with leader of group flung out
- Three HP vehicle, possibly, or a kit
- Skill backing with bloke on board horse-drawn vehicle
- Group from east in Nagasaki or Tokyo
- Composition by Prokofiev for old Russian leadership
- Team sent north in Hirosaki or Tokyo
- Pottery in horse-drawn Russian carriage
- Vehicle making a comeback in Nagasaki or Tokyo
Buddy explains!

The straight part
We know that "vehicle for tour to Winter Palace perhaps" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vehicle for tour to winter palace perhaps = troika.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 TROIKA mean?
TROIKA noun- A Russian carriage drawn by a team of three horses abreast.
- A party or group of three, especially a ruling council of three people in Russian contexts.