Boy lied? Not good (3)
I believe the answer is:
son
'boy' is the definition.
(I know that boy can be written as son)
'lied? not good' is the wordplay.
'lied?' becomes 'song' ('Lied' is German for song).
'not' indicates named letters should be taken away.
'good' becomes 'g' (abbreviation).
'song' with 'g' taken away is 'SON'.
(Other definitions for son that I've seen before include "Human offspring" , "Male offspring" , "Male scion" , "Heir" , "Male child" .)