shrewd
SHROODadjMeaning sharp and clever in practical matters
Memory hook the SHREW-d little shrew. The little shrew sets up his lemonade stand at the top of the hill, right where the hikers are thirstiest: he is shrewd.
Grandma is a shrewd bargainer who never pays full price at the flea market.
In context Selling lemonade at the top of the steep hill instead of at the bottom was a shrewd move: the tired hikers there would gladly pay for a cold drink.
Similar astute, canny, clever, sharp
Opposite naive, gullible
From Middle English shrewe, “a nasty person,” the same word as the small animal; over time the meaning turned from nasty to sharp and clever.