Child star on the radio? (3)
I believe the answer is:
son
'child' is the definition.
(male child)
'star on the radio?' is the wordplay.
'star' becomes 'sun' (the Sun is a star).
'on the radio?' shows a homophone (sound like) (I've seen 'on the radio' mean this).
'sun' is a homophone of 'SON'.
(Other definitions for son that I've seen before include "Human offspring" , "A relative" , "Male offspring" , "Male child" , "The kind of child" .)