Most popular toy for children? (3)
I believe the answer is:
top
I believe this clue is a double definition.
'most popular' is the first definition.
(eg top of the charts)
'toy for children?' is the second definition.
(spinning top)
(Other definitions for top that I've seen before include "Most successful" , "jumper, say?" , "Children's toy" , "Upper side" , "Peak; child's toy" .)