Know-all (8)
'know-all' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for smart alec that I've seen before include "Clever Dick" , "insufferable type" , "Clever person" , "Know-all" , "Clever sort" .)
'know-all' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for wiseacre that I've seen before include "upstart" , "One assuming air of superior wisdom - simpleton" , "Person with an affectation of wisdom" , "Smart alec" , "Self-appointed sage" .)