The Collaborative International Dictionary of English v.0.48:

Clever \Clev"er\, a. [Origin uncertain. Cf. OE. cliver eager,
   AS. clyfer (in comp.) cloven; or clifer a claw, perh.
   connected with E. cleave to divide, split, the meaning of E.
   clever perh. coming from the idea of grasping, seizing (with
   the mind).]
   1. Possessing quickness of intellect, skill, dexterity,
      talent, or adroitness; expert.
      [1913 Webster]

            Though there were many clever men in England during
            the latter half of the seventeenth century, there
            were only two great creative minds.   --Macaulay.
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            Be good, sweet maid, and let who will be clever.
                                                  --C. Kingsley.
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   2. Showing skill or adroitness in the doer or former; as, a
      clever speech; a clever trick. --Byron.
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   3. Having fitness, propriety, or suitableness.
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            'T would sound more clever
            To me and to my heirs forever.        --Swift.
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   4. Well-shaped; handsome. "The girl was a tight, clever wench
      as any was." --Arbuthnot.
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   5. Good-natured; obliging. [U. S.]

   Syn: See Smart.
        [1913 Webster]

WordNet (r) 3.0 (2006):

clever
    adj 1: showing self-interest and shrewdness in dealing with
           others; "a cagey lawyer"; "too clever to be sound" [syn:
           cagey, cagy, canny, clever]
    2: mentally quick and resourceful; "an apt pupil"; "you are a
       clever man...you reason well and your wit is bold"-Bram
       Stoker [syn: apt, clever]
    3: showing inventiveness and skill; "a clever gadget"; "the
       cunning maneuvers leading to his success"; "an ingenious
       solution to the problem" [syn: clever, cunning,
       ingenious]