Floppy disk for children (4)
I believe the answer is:
kids
'for children' is the definition.
('kid' can be a synonym of 'child')
'floppy disk' is the wordplay.
'floppy' indicates anagramming the letters.
'disk' anagrammed gives 'KIDS'.
(Other definitions for kids that I've seen before include "Young goats" , "Teases" , "Youngsters" , "Children" , "They make immature butts" .)