Run out of medicine after initial shot (5)
I believe the answer is:
spill
'run out' is the definition.
(I know that run out can be written as spill)
'medicine after initial shot' is the wordplay.
'medicine' becomes 'pill' (pill is a kind of medicine).
'after' says to put letters next to each other.
'initial shot' becomes 's' (I can't explain this - if you can you should give a lot more credence to this answer).
'pill' put after 's' is 'SPILL'.
'of' is the link.
Can you help me to learn more?
(Other definitions for spill that I've seen before include "Upset; brim over" , "Thin piece of wood used to light a fire" , "Waste from container" , "Let fall accidentally - lighter" , "Allow to drop - fire lighter" .)