Dingbat

[polomac]

—————————
007 X 2
—————————-

[nescio]

double bond?

[mallyh]

double agent

[polomac]

What about bonding layers

[fiction-factory]

double agent is more likely I think, but could be double bond if it was part of a set of science themed ones. The lines and above make me wonder though whether there is another answer