The most common and most likely answer to this crossword clue is the 3 plus 3 letter word OLD HAT
I've seen this crossword clue in The Times
O
L
D
H
A
T
More clues leading to the result OLD HAT
- Unconventional lad, tho’ far from fashionable
- Unfashionable lot had reformed
- One-time bowler possibly superannuated
- Outdated lot had to change
- Like a chestnut horse brought in to lad for grooming
- Dahl novel among books, stale
- Dated bonnet that’s somewhat battered?
- Unfashionable deerstalker, perhaps
- After storm hit methodical mice scuttled out of the ark
- Suffering losses up front, sold what is no longer fresh
Buddy explains!

The straight part
We know that "superannuated" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case superannuated = old hat.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.