The most common and most likely answer to this crossword clue is the 5 letter word GLAND
I've seen this crossword clue in The Times
G
L
A
N
D
More clues leading to the result GLAND
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The straight part
We know that "organ" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case organ = gland.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 GLAND mean?
GLAND noun- An organ that synthesizes a substance, such as hormones or breast milk, and releases it, often into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland).
- A secretory structure on the surface of an organ.
- A compressable cylindrical case and its contents around a shaft where it passes through a barrier, intended to prevent the passage of a fluid past the barrier, such as: