Short of shell? (4)
I believe the answer is:
ammo
This clue might be a double definition.
'short' is the first definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'shell?' is the second definition.
(shell is a kind of ammo)
'of' acts as a link.
Can you help me to learn more?
(Other definitions for ammo that I've seen before include "explosives, perhaps" , "Bullets and bombs, etc (abbr)" , "Bullets etc.(informal)" , "Shot" , "that goes in magazine: ...?" .)