It ends a shot as a substitute (7)
I believe the answer is:
instead
'as a substitute' is the definition.
(I've seen this in another clue)
'it ends a shot' is the wordplay.
'it ends a' anagrams to 'INSTEAD'.
Though, I am unsure how this is indicated.
Can you help me to learn more?
(Other definitions for instead that I've seen before include "Alternatively" , "for a change" , "use this as a replacement" , "Rather - detains (anag)" , "In place (of)" .)