Lead shot originally used with pitch (4)
I believe the answer is:
star
'lead' is the definition.
(I know that lead can be written as star)
'shot originally used with pitch' is the wordplay.
'originally used' indicates taking the first letters.
'with' says to put letters next to each other.
'pitch' becomes 'tar' (synonyms).
The first letter of 'shot' is 's'.
's'+'tar'='STAR'
(Other definitions for star that I've seen before include "Celebrated performer" , "A night light?" , "Celestial body of hot gases" , "chamber" , "Eg, Antares" .)