Supply a firearm part (5)

I believe the answer is:

stock

I believe this is a double definition.

'supply' is the first definition.
(stock can mean a supply or reserve)

'a firearm part' is the second definition.
(I know that stock is a type of firearm part)

(Other definitions for stock that I've seen before include "Equestrian tie" , "displaying little imagination?" , "Cravat worn as part of ridingkit" , "Broth" , "Supply; part of rifle" .)

I've seen this clue in the Evening Standard.

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