Daughter with severe wavering gets merit (7)
I believe the answer is:
deserve
'merit' is the definition.
(I know that merit can be written as deserve)
'daughter with severe wavering' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'with' is a charade indicator (letters next to each other).
'wavering' is an anagram indicator.
'severe' is an anagram of 'eserve'.
'd'+'eserve'='DESERVE'
'gets' acts as a link.
(Other definitions for deserve that I've seen before include "Be entitled to" , "Show one is worthy" , "Merit (something)" , "Severed (anag)" , "Merit, earn" .)