Adopts appropriate child (5,2)
I believe the answer is:
takes on
'adopts' is the definition.
('take on' can be a synonym of 'adopt')
'appropriate child' is the wordplay.
'appropriate' becomes 'take' (appropriate can mean to steal).
'child' becomes 'son' (son is a kind of child).
'take'+'son'='TAKES ON'
(Other definitions for takes on that I've seen before include "Accepts challenge" , "becomes upset" .)