open field

cede the field

To withdraw from any confrontational or potentially confrontational situation; to avoid participating in a competition or contest.

center field

A central role in some activity that requires speed.

debris field

Any area, non-dependent of locale, space, or contour, that contains the debris of wreckage, impact, sinking, or other material that once constituted a complete object. Debris fields can be found at the site of air crashes, water vessel sinking, explosions of buildings, collapses, and other events that render a whole entity into components, pieces, or other non-whole items.

field day

A great time or a great deal to do; a period of bustling activity.

keep a weather eye open

to maintain a background awareness of something; to remain alert to changes without it occupying one's full attention.

keep an eye open

To remain vigilant for someone or something.

keep one's ears open

to listen for important information.

keep one's options open

To not commit to a decision, to keep various options available.