How about "he furrowed his brow"? ("Brow" is singular because it refers to the forehead, not to one of the eyebrows.-- it means "he wrinkled his forehead.") It's not commmon in conversation; it seems sort of old-fashioned or literary. But it's the best I can come up with -- I guess it's something our language is missing. What do other languages say?
"Knitting one's brow" is another.
Edit. According to American Heritage, "brow" can be used in the plural in place of "eye brows" as well as in the singular, meaning "forehead."
Interesting!