The most common and most likely answer to this crossword clue is the 10 letter word IRRATIONAL
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More clues leading to the result IRRATIONAL
- Crazy, Gershwin accepting allotment by lake
- I ran with tailor fittingly making what looks long short
- Crazy Irish sailor turned fifty, touring Scottish island
- Senseless, unruly trial on air
- To leave traitor confused entails regularly following 10 nuts
- Mathematically, like two pieces of pie? Not sensible
- Girl losing her head about allowance a nonsense
- Having broadcast trial on air may be unjustifiable
- Entirely absurd, or just the last two-thirds
- A number out of their minds
Buddy explains!

The straight part
We know that "what looks long short" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what looks long short = irrational.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 IRRATIONAL mean?
IRRATIONAL noun- A real number that can not be expressed as the quotient of two integers, an irrational number.
- Not rational; unfounded or nonsensical.
- Of a real number, that cannot be written as the ratio of two integers.