Discourage daughter and parent's sister (5)
I believe the answer is:
daunt
'discourage' is the definition.
(to daunt is to discourage or intimidate)
'daughter and parent's sister' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'and' says to put letters next to each other.
'parent's sister' becomes 'aunt' (I've seen this before).
'd'+'aunt'='DAUNT'
(Other definitions for daunt that I've seen before include "Make to feel intimidated" , "Discourage" , "Scare off - dismay" , "Dishearten" , "Cause to feel intimidated" .)