Local fellow has a youngster (4)
I believe the answer is:
calf
'a youngster' is the definition.
(I've seen this before)
'local fellow has' is the wordplay.
'has' indicates a hidden word.
'CALF' can be found hidden inside 'local fellow'.
(Other definitions for calf that I've seen before include "Is it above the ankle" , "Young seal" , "Young giraffe - piece of iceberg" , "Roo's mum (A. A. Milne)" , "binding?" .)