Shrewd

Shrewd-adjective
1-showing or possessing intelligence, insight, and sound judgment, especially in business or politics
2-based on good judgment and probably correct
3-inclined to deal with others in a clever, underhanded way
4-piercing or sharp (archaic)

Synonyms
astute
perceptive
cunning
sharp
insightful
sharp-witted
on the ball
wise
canny
smart
clever
naive (antonym)