Prevent rep corrupting some evidence about daughter (8)
I believe the answer is:
preclude
'prevent' is the definition.
(I know that prevent can be written as preclude)
'rep corrupting some evidence about daughter' is the wordplay.
'corrupting' is an anagram indicator.
'some evidence' becomes 'clue' (clue is a kind of evidence).
'about' is an insertion indicator.
'daughter' becomes 'd' (genealogical abbreviation).
'clue' placed around 'd' is 'clude'.
'rep' is an anagram of 'pre'.
'pre'+'clude'='PRECLUDE'
(Other definitions for preclude that I've seen before include "Debar" , "Prevent, prohibit" , "Make impossible" , "bar" , "Rule out or eliminate" .)