Tear after father - or mother (6)
I believe the answer is:
parent
'mother' is the definition.
(I know that mother can be written as parent)
'tear after father' is the wordplay.
'tear' becomes 'rent' (synonyms).
'after' means one lot of letters go next to another.
'father' becomes 'pa' (pa can mean dad or father).
'rent' put after 'pa' is 'PARENT'.
'or' is the link.
(Other definitions for parent that I've seen before include "The company of which others are subsidiaries" , "old man?" , "Mother or father or what they do" , "Bringing together" , "Pa or Ma" .)