In the medico using this, result is relative (6)
I believe the answer is:
cousin
'is relative' is the definition.
(I've seen this before)
'in the medico using this' is the wordplay.
'in' says the answer is hidden in the clue.
'COUSIN' is hidden within 'medico using this'.
'result' is the link.
(Other definitions for cousin that I've seen before include "Kinsman, generally (archaic)" , "US icon is an odd relative" , "Address used among sovereigns" , "An aunt's or uncle's child" , "Family relative" .)