The most common and most likely answer to this crossword clue is the 7 letter word STAMINA
I've seen this crossword clue in The Times
S
T
A
M
I
N
A
More clues leading to the result STAMINA
- Endurance refitting mast in Antarctica, primarily
- Endurance shown by southern girl touring America
- I'm Santa, moving around, showing ability to keep going
- Spot first of athletes covering miles, showing tenacity
- Toughness of floral components
- Strength enlivens pirouettes lacking in energy
- Floor coverings rolled back in area displaying grit
- Sit awkwardly with a man, revealing bottom
- I am playing with ants’ legs
- Am captivated by newly-made Saint's endurance
Buddy explains!

The straight part
We know that "Endurance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case endurance = stamina.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 STAMINA mean?
STAMINA noun- The energy and strength for continuing to do something over a long period of time; power of sustained exertion, or resistance to hardship, illness etc.
- The basic elements of a thing; rudimentary structures or qualities.
- In flowering plants, the structure in a flower that produces pollen, typically consisting of an anther and a filament.