The most common and most likely answer to this crossword clue is the 5 letter word TANKS
I've seen this crossword clue in The Guardian
T
A
N
K
S
More clues leading to the result TANKS
- Beat king with small military units
- Where to put fuel for military vehicles
- Cheers, abandoning hot military vehicles
- Expression of appreciation in Limerick falls flat
- Reservoirs were very smelly, top to bottom
- . Expresses gratitude, after husband leaves, and goes down
- Prison cells smelt bad, from second shift to the last
- Cheers when husband quits and fails badly
- At premiere, Tom Hanks left off sleeveless garments
- Vehicles honked, first travelling to the rear
Buddy explains!

The straight part
We know that "Vehicles" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vehicles = tanks.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 TANKS mean?
TANKS noun- A closed container for liquids or gases.
- An open container or pool for storing water or other liquids.
- A pond, pool, or small lake, natural or artificial.
- The fuel reservoir of a vehicle.
- The amount held by a container; a tankful.
- An armoured fighting vehicle, armed with a gun, and moving on caterpillar tracks.
- (Australian and Indian English) A reservoir or dam.
- A large metal container for holding drinking water for animals, usually placed near a wind-driven water pump, in an animal pen or field.
- By extension a small pond for the same purpose.
- A very muscular and physically imposing person. Somebody who is built like a tank.
- A unit or character designed primarily around damage absorption and holding the attention of the enemy (as opposed to dealing damage, healing, or other tasks).
- A prison cell, or prison generally.
- A metaphorical place where a player goes to contemplate a decision; see in the tank.
- To fail or fall (often used in describing the economy or the stock market); to degenerate or decline rapidly; to plummet.
- To attract the attacks of an enemy target in cooperative team-based combat, so that one's teammates can defeat the enemy in question more efficiently.
- To put (fuel, etc.) into a tank.
- To deliberately lose a sports match with the intent of gaining a perceived future competitive advantage.
- To resist damage; to be attacked without being hurt.
- To contemplate a decision for a long time; to go in the tank.
- A small Indian dry measure, averaging 240 grains in weight.
- A Bombay weight of 72 grains, for pearls.
- To stand; to tolerate.
- Thanks