Daughter is getting behind — almost a total failure? (8)
I believe the answer is:
disaster
'a total failure?' is the definition.
(disaster can mean a complete failure)
'daughter is getting behind almost' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'getting behind almost' becomes 'aster' (I can't justify this - if you can you should believe this answer much more).
'd'+'is'+'aster'='DISASTER'
(Other definitions for disaster that I've seen before include "Extreme event resulting in great loss and misfortune" , "Extreme ruin or misfortune" , "Calamity, sudden great misfortune" , "Terrible calamity" , "Star dies (anag)" .)