The most common and most likely answer to this crossword clue is the 8 letter word CAVALIER
I've seen this crossword clue in Financial Times
C
A
V
A
L
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R
More clues leading to the result CAVALIER
- Patronising Spanish fizz that is bottled in large runs
- Clay held by underground explorer or one on mount
- Devil-may-care Royalist
- Gentleman wants Virginia to remain in saloon?
- Royalist without care
- Disdainful of fizzy wine and pork pie on end of bar
- Devil-may-care underground explorer without any life insurance, initially
- Thoughtless having wine on cruise ship captain finally abandoned
- Incautious having wine and pork pie before run …
- Incautious knight
Buddy explains!

The straight part
We know that "Offhand" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case offhand = cavalier.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 CAVALIER mean?
CAVALIER noun- A military man serving on horse, early modern cavalry officers who had abandoned the heavy armor of medieval knights.
- A gallant: a sprightly young dashing military man.
- A gentleman of the class of such officers, particularly:
- Someone with an uncircumcised penis.
- A defensive work rising from a bastion, etc., and overlooking the surrounding area.
- Of a man: to act in a gallant and dashing manner toward (women).
- Not caring enough about something important.
- High-spirited.
- Supercilious.
- Of or pertaining to the party of King Charles I of England (1600–1649).