Child of resonance (3)
I believe the answer is:
son
'child' is the definition.
(male child)
'of resonance' is the wordplay.
'of' indicates the answer is hidden within the clue.
'SON' is hidden within 'resonance'.
(Other definitions for son that I've seen before include "Young boy" , "The kind of child" , "Male scion" , "A relative" , "Express paper" .)