To a youngster it can mean something extra (3-2)
I believe the answer is:
top-up
'something extra' is the definition.
(I've seen this before)
'to a youngster it can' is the wordplay.
I cannot really see how this works, but
'to' is found in the answer.
'youngster' could be 'pup' (a pup is a young dog) and 'pup' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'mean' acts as a link.
Can you help me to learn more?
(Other definitions for top-up that I've seen before include "Extra addition" , "Replenished drink" , "Amount required to restore something's level" , "Additional amount to restore mobile phone credit, for example" , "Supplement" .)