Worker making a hit with the sergeant major (5)
I believe the answer is:
smith
'worker' is the definition.
(smith is a kind of worker)
'making a hit with the sergeant major' is the wordplay.
'making' is an anagram indicator.
'with' says to put letters next to each other.
'the sergeant major' becomes 'SM' (abbreviation for sergeant major).
'hit' is an anagram of 'ith'.
'ith' put after 'sm' is 'SMITH'.
(Other definitions for smith that I've seen before include "Adam, economist" , "Shoemaker" , "Forger" , "Worker in metals" , "Bessie - - , blues singer" .)