The most common and most likely answer to this crossword clue is the 8 letter word TRIPPERS
T
R
I
P
P
E
R
S
More clues leading to the result TRIPPERS
Buddy explains!

The straight part
We know that "Holidaymaker/one on high" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case holidaymaker/one on high = trippers.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 TRIPPERS mean?
TRIPPERS noun- A person hired to transport goods by boat in the North American fur trade.
- One who trips or stumbles.
- A person experiencing a hallucinogenic trip.
- A tourist.