Move swiftly in one's life's work (6)
I believe the answer is:
career
I believe this is a double definition.
'move swiftly' is the first definition.
(career can mean to race around)
'one's life's work' is the second definition.
(I've seen this before)
'in' acts as a link.
(Other definitions for career that I've seen before include "Life's work path" , "Go at top speed through a working life?" , "Rush - a job for life?" , "Move swiftly" , "History of working life (6)" .)