Hit by a bullet? This will give you a boost (4,2,3,3)
I believe the answer is:
shot in the arm
'hit by a' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'bullet? this will give you a boost' is the wordplay.
I cannot quite see how this works, but
'bullet?' could be 'arm' (bullet is a kind of arm) and 'arm' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for shot in the arm that I've seen before include "Stimulus" , "This will buck you up" , "Fillip" , "Winged" , "Wounded" .)