Guinness who played George Smiley (4)

I believe the answer is:

alec

(Other definitions for alec that I've seen before include "Smart boy?" , "A smart . . . . is a know-all in lace" , "Boy's name (a smart one?)" , "Guinness (a smart lad?)" , "Sir -- Guinness, actor" .)

I've seen this clue in The Wall Street Journal.

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