Family line in dismissive comment by daughter (5)
I believe the answer is:
blood
'family' is the definition.
(blood can mean one's family)
'line in dismissive comment by daughter' is the wordplay.
'line' becomes 'l' (used when specifying particular lines from a poem).
'in' is an insertion indicator.
'dismissive comment' becomes 'boo' (I can't justify this - if you can you should believe this answer much more).
'by' means one lot of letters go next to another.
'daughter' becomes 'd' (genealogical abbreviation).
'l' going inside 'boo' is 'bloo'.
'bloo'+'d'='BLOOD'
Can you help me to learn more?
(Other definitions for blood that I've seen before include "Gore" , "Oxygen-carrying liquid" , "Red fluid" , "Fiery temperament" , "Kinship; temperament" .)