The most common and most likely answer to this crossword clue is the 9 letter word PERIMETER
I've seen this crossword clue in The Times
P
E
R
I
M
E
T
E
R
More clues leading to the result PERIMETER
- Safe old poem's cutting edge
- Right time, curiously, to punch Lord's boundary
- Bounds of archaic poem kept in safe?
- Border: safe crossing eastern edge
- Limit of frost accepted by apostle
- Man in serial denial crosses mud going over boundary
- Ice is within safe limits
- Man once in denial about mud around boundary
- What goes round could possibly be mere tripe
- Border safe? Gulf ruler turns up, being welcomed in
Buddy explains!

The straight part
We know that "edge" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case edge = perimeter.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 PERIMETER mean?
PERIMETER noun- The sum of the distance of all the lengths of the sides of an object.
- The length of such a boundary.
- The outer limits of an area.
- A fortified strip or boundary usually protecting a military position.
- An instrument for determining the extent and shape of the field of vision.