Run in pursuit (6)
I believe the answer is:
career
I believe this is a double definition.
'run' is the first definition.
(thesaurus)
'pursuit' is the second definition.
(I've seen this before)
'in' acts as a link.
(Other definitions for career that I've seen before include "Work history" , "Progression through working life" , "Quick" , "Not intellectual" , "One's professional life" .)