A well-behaved dog carrying the ball back (4)
I believe the answer is:
good
'a well-behaved' is the definition.
(I've seen this before)
'dog carrying the ball back' is the wordplay.
'carrying' is an insertion indicator.
'the ball' becomes 'o' (letter resembling a ball).
'back' is a reversal indicator.
'dog' enclosing 'o' is 'doog'.
'doog' backwards is 'GOOD'.
(Other definitions for good that I've seen before include "Well-behaved, kind, or virtuous" , "Carol character from 1 as of old" , "Obedient" , "Virtuous - valid" , "Of a high standard" .)