Discrimination shown by second divorcee one's married (6)
I believe the answer is:
sexism
'discrimination' is the definition.
(sexism is a kind of discrimination)
'second divorcee one's married' is the wordplay.
'second' becomes 's' (common abbreviation).
'divorcee' becomes 'ex' (I've seen this in other clues).
'one's' becomes 'is' (roman numeral).
'married' becomes 'm'.
's'+'ex'+'is'+'m'='SEXISM'
'shown by' is the link.
(Other definitions for sexism that I've seen before include "Gender-based discrimination" , "Discrimination on grounds of gender" , "Discriminatory or abusive behaviour" , "Prejudice based on gender" , "Prejudice on grounds of gender" .)