A doctor's round for relative (3)
I believe the answer is:
dad
'for relative' is the definition.
(dad is a kind of relative)
'a doctor's round' is the wordplay.
'doctor' becomes 'dd' (Doctor of Divinity).
'round' indicates putting letters inside.
'a' going into 'dd' is 'DAD'.
(Other definitions for dad that I've seen before include "Father, in short" , "Pop, pater" , "Relation" , "Old man" , "Popular father - a palindrome" .)