Discrimination in moving images (6)
I believe the answer is:
ageism
'discrimination' is the definition.
(I know that ageism is a type of discrimination)
'moving images' is the wordplay.
'moving' indicates an anagram (letters are moved around).
'images' is an anagram of 'AGEISM'.
'in' acts as a link.
(Other definitions for ageism that I've seen before include "Discrimination against the elderly" , "Discrimination e.g. against old people" , "Non-PC attitude to senior citizens" , "Images about prejudice against old people" , "Prejudice on grounds of age" .)