Sweet daughter, with ecstasy, flicked back hair (7)
I believe the answer is:
dessert
'sweet' is the definition.
(I know that sweet can be written as Dessert)
'daughter with ecstasy flicked back hair' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'with' means one lot of letters go next to another.
'ecstasy' becomes 'E' (informal term for the drug).
'flicked back' says the letters should be written in reverse.
'hair' becomes 'tress' (tress is a kind of hair).
'tress' written backwards gives 'ssert'.
'd'+'e'+'ssert'='DESSERT'
(Other definitions for dessert that I've seen before include "Fruit and nuts, perhaps" , "End of meal" , "Christmas pudding maybe" , "Sweet, last course of a meal" , "tart?" .)