The most common and most likely answer to this crossword clue is the 9 letter word TROOPSHIP
I've seen this crossword clue in The Daily Telegraph
T
R
O
O
P
S
H
I
P
More clues leading to the result TROOPSHIP
- Military vessel, after overhaul of port, so stylish
- Seagoing vessel for both general and private use?
- Vehicle in the main for those in an engagement?
- One will bring force, sort hippo out
- Nothing unusually posh in a voyage in this
- Services carrier, one in posh port under repair
- Sorry husband entertained by jolly people carrier
- Military transport heading for Tobruk reversed track with it
Buddy explains!

The straight part
We know that "Vehicle in the main for those in an engagement?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vehicle in the main for those in an engagement? = troopship.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 TROOPSHIP mean?
TROOPSHIP noun- A ship used to transport military troops.