The most common and most likely answer to this crossword clue is the 8 letter word PASSPORT
I've seen this crossword clue in The Guardian
P
A
S
S
P
O
R
T
More clues leading to the result PASSPORT
- Travel document graduate left
- Official document father left around ship
- Father’s game: means to travel overseas
- I don't know where ship may be heading, or what passenger may need?
- Hand over booze — It'll get you over the border!
- One needs this to go beyond Dover, for example
- Hand over fortified wine: it must be shown at Immigration
- Travelling requirement in France not fun
- Qualify to get drink producing ID
- Travel essential for Dad’s hobby
Buddy explains!

The straight part
We know that "Travel essential" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case travel essential = passport.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 PASSPORT mean?
PASSPORT noun- An official document normally used for international journeys, which proves the identity and nationality of the person for whom it was issued.
- (by extension) Any document that allows entry or passage.
- Something which enables someone to do or achieve something.