Urchin who hasn’t finished playing (5)
I believe the answer is:
gamin
'urchin who hasn't' is the definition.
'gamin' can be an answer for 'urchin' (gamin is a kind of urchin). I'm not certain of the remainder of the definition.
'finished playing' is the wordplay.
'finished' becomes 'gam' (I can't justify this - if you can you should give a lot more credence to this answer).
'playing' becomes 'in'.
'gam'+'in'='GAMIN'
Can you help me to learn more?
(Other definitions for gamin that I've seen before include "stray" , "Street urchin or impudent child" , "Little urchin" , "Waif" , "Street kid" .)