An inexperienced youth could be fired (4)
I believe the answer is:
colt
I believe this clue is a double definition.
'an inexperienced youth' is the first definition.
'could be fired' is the second definition.
(colt is a type of gun)
(Other definitions for colt that I've seen before include "with a hefty kick?" , "H [HORSE]" , "firearm" , "Young horse - gun" , "Young animal" .)