Playmate a girl's too young for (3,3)
I believe the answer is:
toy boy
'playmate a girl's too' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'young for' is the wordplay.
I cannot quite see how this works, but
'young' could be 'boy' (young boy) and 'boy' is found in the answer.
'for' could be 'to' (eg both can mean 'in the opinion of') and 'to' is found in the answer.
A single letter 'y' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for toy boy that I've seen before include "Much younger male lover of older woman" , "Gigolo" , "Older woman's fancy" , "Young male lover of older woman" , "Woman's young lover" .)