The most common and most likely answer to this crossword clue is the 5 letter word LUCKY
I've seen this crossword clue in Financial Times
L
U
C
K
Y
Buddy explains!

The straight part
We know that "fortunate" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fortunate = lucky.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 LUCKY mean?
LUCKY adjective- (of people) Favoured by luck; fortunate; having good success or good fortune
- Producing, or resulting in, good fortune