The most common and most likely answer to this crossword clue is the 8 plus 5 letter word FREQUENT FLIER
I've seen this crossword clue in The Daily Telegraph
F
R
E
Q
U
E
N
T
F
L
I
E
R
Buddy explains!
The straight part
We know that "Jet-setter who gets discount" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case jet-setter who gets discount = frequent flier.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.