The most common and most likely answer to this crossword clue is the 8 letter word LENTICEL
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Buddy explains!
The straight part
We know that "little breathing space" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case little breathing space = lenticel.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 LENTICEL mean?
LENTICEL noun- One of the small, oval, rounded spots upon the stem or branch of a plant, from which the underlying tissues may protrude or roots may issue, either in the air, or more commonly when the stem or branch is covered with water or earth.
- A small, lens-shaped gland on the underside of some leaves.