The most common and most likely answer to this crossword clue is the 9 letter word SECLUSION
I've seen this crossword clue in Financial Times
S
E
C
L
U
S
I
O
N
More clues leading to the result SECLUSION
Buddy explains!

The straight part
We know that "retirement" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case retirement = seclusion.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 SECLUSION mean?
SECLUSION noun- The act of secluding, shutting out or keeping apart.
- The state of being secluded or shut out, as from company, society, the world, etc.; solitude.
- A secluded, isolated or private place.
- The mature phase of the extratropical cyclone life cycle.