Often carries a slightly negative nuance of being clever in a shallow or cunning way, rather than deeply wise. Can be used both as a noun and as a na-adjective.
He passed the exam by a clever little trick.
That child is shrewd and quickly reads adults' expressions.
Compound of 小 (small, petty) and 利口 (clever, smart). The prefix 小 adds a nuance of 'small-scale' or 'shallow' cleverness.