Decorated knight in love with daughter (7)
I believe the answer is:
adorned
'decorated' is the definition.
('adorn' can be a synonym of 'decorate')
'knight in love with daughter' is the wordplay.
'knight' becomes 'n' (chess).
'in' means one lot of letters goes inside another.
'love' becomes 'adore' (adoring is a kind of loving**).
'with' means one lot of letters go next to another.
'daughter' becomes 'd'.
'n' put inside 'adore' is 'adorne'.
'adorne'+'d'='ADORNED'
(Other definitions for adorned that I've seen before include "Bedecked while Don read" , "done up" , "Embellished, decorated" , "Put on finery" , "Decorated, bedecked" .)