Definition of clear-thinking:
(adj) :
Transparent in colour.
(adj) :
Bright; luminous; not dark or obscured.
(adj) :
Free of obstacles.
(adj) :
Without clouds.
(adj) :
(meteorology) Of the sky, such that less than one eighth of its area is obscured by clouds.
(adj) :
Free of ambiguity or doubt; easily understood.