The most common and most likely answer to this crossword clue is the 10 letter word ELONGATION
I've seen this crossword clue in The Times
E
L
O
N
G
A
T
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Buddy explains!
The straight part
We know that "Stretching" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case stretching = elongation.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 ELONGATION mean?
ELONGATION noun- The act of lengthening
- The state of being lengthened
- That which lengthens out; continuation.
- The ratio of the extension of a material to the length of the material prior to stretching.
- Removal to a distance; withdrawal; a being at a distance; distance.
- The angular distance of a planet from the sun