She found out about the car crash in the investigation (6)
I believe the answer is:
search
'investigation' is the definition.
(search is a kind of investigation)
'she found out about the car crash' is the wordplay.
'found out' is an anagram indicator (discovered out of the normal letter order).
'about' is an insertion indicator.
'crash' is an anagram indicator.
'she' with letters rearranged gives 'seh'.
'car' is an anagram of 'arc'.
'seh' going around 'arc' is 'SEARCH'.
'in the' acts as a link.
(Other definitions for search that I've seen before include "investigation . . . ." , "Scour, seek" , "Look for something or someone, perhaps chaser" , "Forage, quest" , "Try to find something by looking" .)