Her career's disrupted by investigator (10)
I believe the answer is:
researcher
'investigator' is the definition.
('researcher' can be a synonym of 'investigator')
'her career's disrupted by' is the wordplay.
'disrupted' indicates anagramming the letters.
'by' means one lot of letters go next to another.
'careers' with letters rearranged gives 'researc'.
'her' after 'researc' is 'RESEARCHER'.
(Other definitions for researcher that I've seen before include "Person investigating" , "analyst" , "One seeks information" , "One investigating" , "One making investigations" .)