The most common and most likely answer to this crossword clue is the 4 letter word SANE
I've seen this crossword clue in Independent
S
A
N
E
More clues leading to the result SANE
- Rational as painter ignoring the odds
- Sensible article plugging southeast
- All there is can be invisible at first
- Lucid? Regularly wiped out. Slàinte!
- Reasonable European supports Spain intermittently
- All there ignore nasty sandwiches served up
- Sensible artisan eats sandwiches
- Sensible article introduced by leaders in Sunday Express
- Contrarily, Ena’s being reasonable
- Stable entering Derby’s a newcomer
Buddy explains!

The straight part
We know that "Reasonable" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case reasonable = sane.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 SANE mean?
SANE adjective- Being in a healthy condition; not deranged; thinking rationally.
- Mentally sound; possessing a rational mind; having the mental faculties in such condition as to be able to anticipate and judge the effect of one's actions in an ordinary manner.
- Rational; reasonable; sensible.