Discrimination when manipulating images (6)
I believe the answer is:
ageism
'discrimination' is the definition.
(I know that ageism is a type of discrimination)
'manipulating images' is the wordplay.
'manipulating' indicates an anagram (I've seen this in other clues).
'images' with letters rearranged gives 'AGEISM'.
'when' is the link.
(Other definitions for ageism that I've seen before include "Images about prejudice against old people" , "Form of discrimination" , "Discrimination on grounds of age" , "Bad attitude to the grey" , "Prejudice or bias against old people" .)