Turning to best toy (8,3)
I believe the answer is:
spinning top
'toy' is the definition.
(I know that spinning top is a type of toy)
'turning to best' is the wordplay.
'turning' becomes 'spinning' (I've seen this before).
'to best' becomes 'top' (top can mean the very best).
'spinning'+'top'='SPINNING TOP'
(Other definitions for spinning top that I've seen before include "Child's toy" , "Child's plaything" , "Revolutionary toy" .)