Relative in house at last in French city (5)
I believe the answer is:
niece
'relative' is the definition.
(niece is a kind of relative)
'house at last in french city' is the wordplay.
'at last' suggests the final letters.
'in' indicates putting letters inside.
'french city' becomes 'nice' (Nice is a French city).
The final letter of 'house' is 'e'.
'e' going into 'nice' is 'NIECE'.
'in' is the link.
(Other definitions for niece that I've seen before include "One of the family" , "Young female relative" , "Brother or sister's daughter" , "Family girl" , "A sibling's daughter" .)