Smart guy? (4)
'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?" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">smart guy</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>