Goes around getting the job done - it's a character builder (4)
I believe the answer is:
gene
'goes around getting the job done' is the definition.
I can't judge whether this defines the answer.
'a character builder' is the wordplay.
'a character' becomes 'g'.
'builder' becomes 'ene' (I am not sure about this - if you are sure you should believe this answer much more).
'g'+'ene'='GENE'
'it's' is the link.
Can you help me to learn more?
(Other definitions for gene that I've seen before include "Hereditary determinant" , "The Selfish -- (Dawkins)" , "A segment of DNA" , "- - Kelly, dancer" , "Basic unit of heredity" .)