The most common and most likely answer to this crossword clue is the 11 letter word PARASAILING
I've seen this crossword clue in Independent
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Buddy explains!

The straight part
We know that "Gliding along" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gliding along = parasailing.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 PARASAILING mean?
PARASAILING verb- To take part in the recreational activity of parasailing.
- A recreational activity where a person is towed behind a vehicle (usually a boat) while attached to a specially designed parachute, known as a parasail.