The most common and most likely answer to this crossword clue is the 8 letter word JAUNTING
I've seen this crossword clue in The Times
J
A
U
N
T
I
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G
Buddy explains!
The straight part
We know that "Going on excursion?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case going on excursion? = jaunting.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 JAUNTING mean?
JAUNTING verb- To ramble here and there; to stroll; to make an excursion.
- To ride on a jaunting car.
- To jolt; to jounce.
- The act of taking a jaunt.