Clearheaded
ahd-5
adjective.
Having a clear, orderly mind; sensible.
Wiktionary, Creative Commons Attribution/Share-Alike License
adjective.
Having the
ability
to
think
clearly
and
act
appropriately
Word Usage
"It’s therefore what I might call a clearheaded lunatic, who’s following a definite line of activity and is sufficiently circumspect to take precautions.”"