Smart guy (5)
'smart guy' is the definition.
(as in the phrase 'smart Alec')
This is all the clue.
(Other definitions for alec that I've seen before include "Actor Guinness is smart" , "Sir -- Guinness, actor" , "Smart chap" , "Boy's name (a smart one?)" , "Smart man?" .)
'smart guy' is the definition.
(I've seen this in another clue)
This is all the clue.