Naughty child's manner creating damage (6)
I believe the answer is:
impair
'damage' is the definition.
(impairing is a kind of damaging)
'naughty child's manner' is the wordplay.
'naughty child' becomes 'imp' (I've seen this before).
'manner' becomes 'air' (air is a kind of manner).
'imp'+'air'='IMPAIR'
'creating' acts as a link.
(Other definitions for impair that I've seen before include "Hinder" , "Weaken, damage" , "Damage or handicap" , "Spoil strength, quality of" , "'Mar, spoil (6)'" .)