The most common and most likely answer to this crossword clue is the 5 letter word SOBER
I've seen this crossword clue in The Guardian
S
O
B
E
R
More clues leading to the result SOBER
- Serious honour senior accepts
- Cry over queen’s grave
- One who cries half-heartedly without having a drink
- Thus beer made half-heartedly is not drunk
- Succeeded with month — after missing the first three — avoiding drink
- Solemn robes altered
- Rose wobbles, clutching top of bottle, clearly not this!
- Serious award given to senior …
- Solemn one crying half-heartedly
- Cry tears regularly becoming dry
Buddy explains!
The straight part
We know that "rational" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rational = sober.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 SOBER mean?
SOBER verb- (often with up) To make or become sober.
- (often with up) To overcome or lose a state of intoxication.
- To moderate one's feelings
- Not drunk; not intoxicated
- Not given to excessive drinking of alcohol
- Moderate; realistic; serious; not playful; not passionate; cool; self-controlled
- Dull; not bright or colorful
- Subdued; solemn; grave
- Poor; feeble