Offspring of a rock idol (3)
I believe the answer is:
kid
'offspring' is the definition.
(kid is a kind of offspring)
'of a rock idol' is the wordplay.
'of' indicates the answer is hidden within the clue.
'KID' is hidden in the letters of 'a rock idol'.
(Other definitions for kid that I've seen before include "Soft leather" , "Sort of glove" , "Josh" , "Jest" , "Young animal or child" .)