The most common and most likely answer to this crossword clue is the 5 letter word PLAZA
I've seen this crossword clue in The Guardian
P
L
A
Z
A
More clues leading to the result PLAZA
- Square loaf mostly devoured by old man
- Pal, jazzman, regularly seen in square
- Old man confining most of rest in open space
- Some hoopla, zany, in public area
- Here the Spanish may meet Dad carrying short loaf
- Old jazz uncovered in dad’s open space
- Place first and last letter next to a square
- Extreme characters engaged in a lot of sport in open space
- Priest left street directory on a square
- Contrive to wipe out each unfinished city square
Buddy explains!

The straight part
We know that "open space" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case open space = plaza.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 PLAZA mean?
PLAZA noun- A town's public square.
- An open area used for gathering in a city, often having small trees and sitting benches.
- A strip mall.