Scare her running investigation (8)
I believe the answer is:
research
'investigation' is the definition.
(research is a kind of investigation)
'scare her running' is the wordplay.
'running' indicates anagramming the letters.
'scare'+'her'='scareher'
'scareher' is an anagram of 'RESEARCH'.
(Other definitions for research that I've seen before include "Examination" , "material for investigation" , "Look into" , "Systematic investigation to establish facts" , "Experimentation" .)