Children serve as topic for debate (5)
I believe the answer is:
issue
I believe this clue is a triple definition!
'children' is the first definition.
(issue can mean someone's offspring)
'serve' is the second definition.
(thesaurus)
'as' is a link.
'topic for debate' is the third definition.
(I've seen this before)
(Other definitions for issue that I've seen before include "Subject, result, or publication" , "Important question" , "Topic; give out" , "Subject of debate" , "Send out or distribute for use" .)