Youngster's top outlaw, extremely immature (6)
I believe the answer is:
hoodie
'youngster's top' is the definition.
'hoodie' can be an answer for 'top' (type of clothing top ). I'm unsure of the 'youngster's' bit.
'outlaw extremely immature' is the wordplay.
'outlaw' becomes 'hood' (hood is a kind of outlaw).
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'immature' with its centre taken out is 'ie'.
'hood'+'ie'='HOODIE'
Can you help me to learn more?
(Other definitions for hoodie that I've seen before include "Sweatshirt with head-covering" , "Youth's top" , "'Uniform' often associated with ASBO offenders (variant spelling)" , "Crow; cowled youth" , "Casual jacket" .)