Daughter having secret meal (6)
I believe the answer is:
dinner
'meal' is the definition.
(I know that dinner is a type of meal)
'daughter having secret' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'having' says to put letters next to each other.
'secret' becomes 'inner' (I've seen this before).
'd'+'inner'='DINNER'
(Other definitions for dinner that I've seen before include "serving in 20 [MESS] ?" , "Repast" , "Supper" , "grub" , "Evening meal" .)