Relative security needed by one? (5)
I believe the answer is:
uncle
I believe this clue is a double definition.
'relative' is the first definition.
(I know that relative can be written as uncle)
'security needed by one?' is the second definition.
(pawnbrokers or 'uncles' take items as security)
(Other definitions for uncle that I've seen before include "Sam, perhaps" , "Law enforcement body" , "one who's taken the pledge" , "Brother of one's parent" , "Dad's brother" .)