Bad shortage limiting soft ammo once (9)
I believe the answer is:
grapeshot
'ammo once' is the definition.
(historic type of ammunition)
'bad shortage limiting soft' is the wordplay.
'bad' indicates an anagram.
'limiting' indicates putting letters inside.
'soft' becomes 'p' (musical abbreviation for 'piano').
'shortage' anagrammed gives 'graeshot'.
'graeshot' going around 'p' is 'GRAPESHOT'.
(Other definitions for grapeshot that I've seen before include "slugs?" , "Short page (anag) - ammunition for cannon" , "Great Balls of Fire" , "Describing ammunition" , "Small projectiles fired from cannon" .)