French city hosting English relation (5)
I believe the answer is:
niece
'relation' is the definition.
(I know that niece is a type of blood relation)
'french city hosting english' is the wordplay.
'french city' becomes 'Nice' (Nice is a French city).
'hosting' indicates putting letters inside (inserted letters are welcomed in or hosted).
'english' becomes 'E' (abbreviation).
'nice' enclosing 'e' is 'NIECE'.
(Other definitions for niece that I've seen before include "Criminal" , "Brother or sister's daughter" , "Brother's girl" , "[PRIEST'S] daughter?" , "A sibling's daughter" .)