The most common and most likely answer to this crossword clue is the 7 letter word ELASTIC
I've seen this crossword clue in The Daily Telegraph
E
L
A
S
T
I
C
More clues leading to the result ELASTIC
- Resilient characters from Castile
- Giving support that boxers need
- Bouncy castle I played with
- Resilient European to remain in charge
- New form of lace — it’s stretchy
- Stretchy base: perhaps Tupperware loses lid
- Bouncy castle collapses, trapping one
- One held captive in castle, tragically yielding
- Like some bands? Endure one in English clubs
- The Spanish bubblyis reminiscent of rubber
Buddy explains!

The straight part
We know that "stretchy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case stretchy = elastic.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 ELASTIC mean?
ELASTIC noun- An elastic material used in clothing, particularly in waistbands and cuffs.
- An elastic band.
- Capable of stretching; particularly, capable of stretching so as to return to an original shape or size when force is released.
- Made of elastic.
- Of clothing, elasticated.
- Sensitive to changes in price.
- Springy; bouncy; vivacious
- Able to return quickly to a former state or condition, after being depressed or overtaxed; having power to recover easily from shocks and trials.