Joy's topless relative (7)
I believe the answer is:
elation
'joy's' is the definition.
(elation is a kind of joy)
'topless relative' is the wordplay.
'topless' means to remove the first letter.
'relative' becomes 'relation' (synonyms).
'relation' with its first letter removed is 'ELATION'.
(Other definitions for elation that I've seen before include "High feeling?" , "Euphoria of toenail" , "It's a great feeling!" , "There's great joy" , "Feeling of delight or pride" .)