Child, second, performing (3)
I believe the answer is:
son
'child' is the definition.
(son is a kind of child)
'second performing' is the wordplay.
'second' becomes 's' (common abbreviation**).
'performing' becomes 'on' (I've seen this in other clues).
's'+'on'='SON'
(Other definitions for son that I've seen before include "Express paper" , "Human offspring" , "Native" , "Male descendant" , "A relative" .)