becloud

To cause to become obscure or muddled.

[…] Intemperance and Superfluity beclouds the Mind, dulls the edge of the Apprehension, and brings upon it an unmanly Languor, bearing down all the noble Faculties of the Soul into Ignorance and Stupidity […]

[…] conscience was not to be perverted by the sophistry which had beclouded my reason.

To cover or surround with clouds.

And then while you're a cooking, they say, / Such a fogo beclouds all the room, / That the girls have to group out the way, / In search of the tongs or the broom.

Day light began to forsake the red-room; it was past four o’clock, and the beclouded afternoon was tending to drear twilight.

To cast in a negative light, cast a pall over, darken.

What Fury has possest thee? What strange fit Usurps thy patience, and beclouds thy brow?

1856, Abraham Lincoln, speech given on 19 May, 1856 in Speeches and Letters of Abraham Lincoln, London: J.M. Dent, 1907, p. 46, We live in the midst of alarms; anxiety beclouds the future; we expect some new disaster with each newspaper we read.