Song composed about a daughter (8)
I believe the answer is:
serenade
'song' is the definition.
(I know that serenade is a type of song)
'composed about a daughter' is the wordplay.
'composed' becomes 'serene' (I've seen this in another clue).
'about' means one lot of letters goes inside another.
'daughter' becomes 'd' (genealogical abbreviation).
'a'+'d'='ad'
'serene' placed around 'ad' is 'SERENADE'.
(Other definitions for serenade that I've seen before include "Musical piece" , "Musical performance, under a lady's window?" , "It's played or sung at a lover's window" , "Lover's song" , "Song sung by suitor" .)