clearheaded

Pilots who smoke perform more poorly than clear-headed pilots on simulators—and that lasts 24 hours or more.

He was a sober, clear-headed, studious and somewhat taciturn boy, quick to perceive and prompt to act.

He was, notwithstanding his apparent enthusiasm and recklessness, extremely methodical and clear-headed.

Clear-headed politicians saw at once that the tenants had played the game and lost.