Extract container for ammunition (4)
I believe the answer is:
clip
'extract' is the definition.
(thesaurus)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for clip that I've seen before include "It can hold cartridges and hair" , "Container for cartridges" , "Extract; cartridge" , "Cartridge container and piece of film" , "Short piece of film" .)