Harps on about these children (7)
I believe the answer is:
orphans
'these children' is the definition.
(orphan is a kind of child)
'harps on about' is the wordplay.
'about' indicates anagramming the letters.
'harps'+'on'='harpson'
'harpson' with letters rearranged gives 'ORPHANS'.
(Other definitions for orphans that I've seen before include "children like Annie?" , "unprotected young?" , "Ran shop (anag)" , "They have lost both parents" , "Machines phased out" .)