Threadbare children: yours, not ours! (5)
I believe the answer is:
seedy
'threadbare' is the definition.
(thesaurus)
'children yours not ours' is the wordplay.
'children' becomes 'seed' (I've seen this before).
'not' suggests deleting specific letters.
'yours' with 'ours' taken out is 'y'.
'seed'+'y'='SEEDY'
(Other definitions for seedy that I've seen before include "Sordid, squalid" , "Not well turned out" , "run down" , "Sleazy, sordid" , "Off-colour" .)