Close relation lives on benefits in the end (3)
I believe the answer is:
sis
'close relation' is the definition.
(short for sister)
'lives on benefits in the end' is the wordplay.
'lives' becomes 'is' ('be' can be a synonym of 'live').
'on' is a charade indicator (letters next to each other).
'in the end' says to take the final letters.
The last letter of 'benefits' is 's'.
'is' put after 's' is 'SIS'.
(Other definitions for sis that I've seen before include "Little sibling" , "Secret Intelligence Service (abbreviation)" , "Family member (informal)" , "Girl" , "Sibling (informal)" .)