Slide, first to last, for children (4)
I believe the answer is:
kids
'children' is the definition.
('kid' can be a synonym of 'child')
'slide first to last' is the wordplay.
'slide first' becomes 's' (kst letter of 'slide').
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'last' becomes 'kid' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
's' put after 'kid' is 'KIDS'.
'for' is the link.
Can you help me to learn more?
(Other definitions for kids that I've seen before include "fools" , "Children" , "Young goats" , "Youngsters" , "They make immature butts" .)