na-adjective, noun
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.
彼は小利口なやり方で試験をパスした。
He passed the exam by a clever little trick.
あの子は小利口で、すぐに大人の顔色をうかがう。
That child is shrewd and quickly reads adults' expressions.
賢い means 'wise' or 'intelligent' with a strong positive connotation, unlike 小利口 which can be slightly derogatory.
Compound of 小 (small, petty) and 利口 (clever, smart). The prefix 小 adds a nuance of 'small-scale' or 'shallow' cleverness.