Delight of beheaded kinsman (7)
I believe the answer is:
elation
'delight' is the definition.
(I've seen this before)
'beheaded kinsman' is the wordplay.
'beheaded' means to remove the first letter (the head of the word is removed).
'kinsman' becomes 'relation' (I've seen this in another clue).
'relation' with its initial letter removed is 'ELATION'.
'of' acts as a link.
(Other definitions for elation that I've seen before include "Bliss" , "Feeling of joy for it alone" , "Feeling of joy from toenail" , "Feeling of joy and pride" , "It's a great feeling!" .)