Relative in northeast: that's a relief (6)
I believe the answer is:
nephew
'relative' is the definition.
(type of relative)
'north-east that's a relief' is the wordplay.
'north east' becomes 'ne'.
'that's a relief' becomes 'phew' (phew is an expression of relief).
'ne'+'phew'='NEPHEW'
'in' is the link.
(Other definitions for nephew that I've seen before include "Sister's son" , "Male relative" , "Edward V to Richard III relation" , "A young male relation" , "Sibling's son" .)