As a child Capone appears to be all there (5)
I believe the answer is:
total
'as a' is the definition.
I can't tell whether this defines the answer.
'child capone appears to be all there' is the wordplay.
I cannot really see how this works, but
'child' could be 'tot' (term for a young child) and 'tot' is located in the answer.
'capone' could be 'al' (gangster Al Capone) and 'al' is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for total that I've seen before include "Completely destroy" , "to give the final figure" , "Absolute; sum" , "Complete sum" , "Everything added together" .)