Couple finally dropping off obscure relative (5)
I believe the answer is:
uncle
'relative' is the definition.
(uncle is a kind of relative)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for uncle that I've seen before include "Law enforcement body" , "Male family member" , "He's related" , "takes the pledge" , "Brother of one's parent" .)