Daughter to back point (3)
I believe the answer is:
dot
'point' is the definition.
(I know that point can be written as dot)
'daughter to back' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'back' is a reversal indicator.
'to' reversed gives 'ot'.
'd'+'ot'='DOT'
(Other definitions for dot that I've seen before include "'Spot, tiny mark (3)'" , "Speck or period" , "Flyspeck: period in a web address" , "Small round spot" , "Very small circular shape" .)